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ARTIFICIAL 
CROWN-,  BRIDGE-,  AND   PORCELAIN-WORK 

EVANS 


A  PRACTICAL  TREATISE 


ON 


ARTIFICIAL 

CROWN-,  BRIDGE-,  AND 
PORCELAIN-WORK 


BY 

GEORGE  EVANS,  D.D.S.,  F.A.A.D.S. 

NEW  YORK  STATE  BOARD  DENTAL  EXAMINER;  FORMERLY  CLINICAL  PROFESSOR  COLLEGE  OF  DENTAL 

AND   ORAL  SURGERY,  NEW  YORK;  LECTURER  BALTIMORE   COLLEGE  OF  DENTAL  SURGERY; 

POST-GRADUATES  LECTURER  ROYAL   COLLEGE   OF  DENTISTRY,  TORONTO,   CANADA; 

MEMBER  OF   THE   NATIONAL  DENTAL  ASSOCIATION:  OF  THE  DENTAL  SOCIETY 

OF    THE    STATE    OF     NEW     YORK;     OF     THE     FIRST     DISTRICT     DENTAL 

SOCIETY  OF   THE  STATE   OF   NEW  YORK;   OF  THE  ODONTOLOGICAL 

society;  OF  THE  AMERICAN   ACADEMY   OF  DENTAL   SURGERY; 

VICE-PRESIDENT   OF  THE   NEW   YORK  DENTAL   CLUB;  ETC. 


EIGHTH  EDITION,  REVISED  AND  ENLARGED 
WITH  1143  ILLUSTRATIONS 


PHILADELPHIA 

P.   BLAKISTON'S  SON  &  CO. 

1012   WALNUT   STREET 


or) , 


Copyright,  1888,  by  George  Evans. 
Copyright,  1889,  by  George  Evans. 
Copyright,  1893,  by  George  Evans. 
Copyright,  1893,  by  George  Evans. 
Copyright,  1896,  by  George  Evans. 
Copyright,  1900,  by  George  Evans. 
Copyright,  1905,  by  George  Evans. 
Copyright,  1920,  by  George  Evans. 


TSE     ai^PLE     PKESS     'r  O  US.    I»A 


To 
William  Carr,  M.D.,  D.D.S. 

in  acknowledgment  of  his  professional  eminence 
and  his  services  for  dental  legislation  and  its  en- 
forcement in  the  State  of  New  York,  this  volume 
is  respectfully  inscribed  by 

THE  AUTHOR. 


PREFACE  TO  THE  EIGHTH  EDITION 


Since  the  publication  of  the  last  edition  of  this  treatise  on  crown-, 
bridge-  and  procelain-work,  the  evolution  of  the  art  has  produced 
changes  and  modifications  in  the  methods  of  its  practice  that  require 
a  revision  for  the  present  edition  so  extensive  as  to  constitute  practically 
a  new  book.  As  in  former  editions,  the  intention  is  to  meet  the  require- 
ments of  a  treatise  for  college  and  post-graduate  study,  and  as  well  a 
reference  book  for  the  practitioner.  Like  all  text-books,  it  is  largely  a 
compilation  of  the  most  accepted  methods  in  practice,  including  also 
those  that  are  novel  which  in  my  opinion  are  worthy  of  consideration 
or  adoption  as  tending  to  facilitate  the  performance  of  better  opera- 
tions in  a  practical  way. 

In  presenting  to  the  dental  profession  the  subjects  embraced  in 
this  treatise  I  have  been  guided  by  personal  experience  of  nearly  forty 
years  specially  devoted  to  their  study  and  practice. 

The  discussion  of  pathological  conditions,  surgical  operations,  and 
of  therapeutic  indications,  metallurgy,  and  the  mechanical  processes 
involved  in  the  construction  of  appliances,  has  been  limited  to  their 
direct  relationship  to  the  work  in  hand.  Dental  students,  and  practi- 
tioners still  more,  are  supposed  to  be  generally  informed  respecting 
these  topics  with  facilities  for  ready  reference  to  works  specially  de- 
voted to  them  and  to  adjunct  or  collateral  subjects. 

The  endeavor  in  this  treatise  has  always  been  to  make  the  text 
comprehensive  without  bulkiness,  concise  without  the  sacrifice  of 
clearness  to  brevity  of  statement,  which  latter  is  much  assisted  by 
reference  to  numerous  illustrations,  and  to  avoid  repetition  except 
when  it  conduced  to  better  understanding.  With  the  latter  object  in 
view  the  text  is  divided  into  seven  sections,  and  a  preliminary  explana- 
tion and  description  of  processes  specially  connected  with  the  work  is 
given  in  the  first  section,  which  is  thereafter  referred  to  only  when 
necessary  for  the  addition  of  supplementary  descriptive  matter  con- 
nected with  special  operations. 

In  the  present  edition  the  effort  is  made,  even  more  seriously  than 
in  those  that  preceded  it,  to  impress  the  importance  from  a  physiological 
standpoint  of  the  use  of  methods  that  permit  the  attainment  of  the 
desired  results   without   the  devitalization  of  pulps,  and  thus  avoid 


viii  PREFACE   TO   THE  EIGHTH  EDITION 

the  chance  of  subsequent  focal  infection,  and  with  the  least  mutilation 
of  teeth,  and  the  least  exposure  of  metal.  The  subject  of  fixed  and 
removable  bridge- work  is  impartially  discussed  and  the  merits  and  dis- 
advantages of  each  clearly  presented. 

The  aim  throughout  the  work  has  been  to  give  to  the  dental  profes- 
sion an  up-to-date  compilation  of  methods  of  practice.  In  this  I  have 
been  guided  by  the  writings  and  instructions  and  the  opinions  personally 
given  me  by  specially  qualified  members  of  the  profession,  as  well  as 
my  own  experience.  I  desire  particularly  to  acknowledge  my  indebted- 
ness for  suggestions  on  removable  crown-  and  bridge-work  to  Drs. 
Ralph  B.  Reitz,  R.  F.  Getz,  C.  Barton  Addie,  Charles  F.  Ash,  Herman 
E.  S.*  Chayes,  George  Evans  Jr.,  and  Mr.  H.  A.  Gollobin,  and  to  lec- 
tures by  Dr.  Frederick  A.  Peeso,  and  Mr.  Louis  J.  Weinstein;  on  inlay 
work  to  Drs.  Henry  W.  Gillett,  William  Dwight  Tracy,  Frank  T, 
Van  Woert,  Alfred  R.  Starr,  Herbert  L.  Wheeler,  and  William  A. 
Capon;  for  courtesy  in  the  use  of  illustrations  or  models,  to  Drs.  F.  T. 
Van  Woert,  F.  R.  Getz,  Richard  Blum,  H.  Schwitzer,  F.  E.  Roach, 
H.  E.  S.  Chayes  and  Messrs.  Louis  Weinstein,  H.  A.  Gollobin  and  J. 
Zirikian. 

BOOKS  OF  REFERENCE 

American  System  of  Dentistry. 

Johnson's  Text-book  of  Operative  Dentistry. 

Kirk's  American  Text-book  of  Operative  Dentistry. 

Prothero's  Prosthetic  Dentistry. 

Turner's  American  Text-book  on  Prosthetic  Dentistry.    . 

Goslee's  Principles  and  Practice  of  Crown-  and  Bridge-work. 

Peeso's  Crown-  and  Bridge-work. 

Hovestad's  Principles  and  Technique  of  Crowns  and  Bridges. 

Black's  Descriptive  Anatomy  of  the  Human  Teeth. 

Geokge  Evans. 
55  West  39th  St.,  New  York, 
May  1,  1920 


CONTENTS 


PART  I 

MATERIALS  AND  PROCESSES  USED  IN  CROWN-  AND 
BRIDGE-WORK 


CHAPTER  I 

Page 

Preparatory  Requirements 3 

Instruments — Tools — Precious  metals — Base  metals — Materials  and  acces- 
sories. 

CHAPTER  n 

Plates  and  Solders 7 

Platinum — Platinum  foil  and  wire — Platinum  and  gold  for  collars — Iri- 
dium— Gold — Gold  alloys — Formulas  for  crown-work — Clasp  gold — Gold 
platinum  lined  plate — Platinized  gold — Melting  and  refining  of  gold  scraps 
— Gold  solders^ — Hard  gold  solder — Peeso  formulas — Fluxed  solder  filings 
— Platinum  solder — Silver  solder — Flux — Jeweler's  liquid  flux. 

CHAPTER  III 

Other  Materials 14 

Fusible  alloys — Formulas — Impression  compound — Dental  lac — Moldine 
— Wax  cement^ — To  secure  adhesion  of  wax  to  metal  or  porcelain — Por- 
celain teeth  or  facings — Essentials  of  porcelain  teeth — Fractures  in  porce- 
lain teeth,  causes  of — Changes  of  shade  in  baking  and  soldering — Veneers 
— To  change  shape  or  contour  of  a  porcelain  tooth. 

CHAPTER  IV 

Appliances  and  Methods 18 

Impression  trays — Articulators — Impressions — Sectional  impressions — 
Roach  sectional  impression  tray — Models — A  hard  surface — To  harden 
plaster  models — Artificial  stone — Articulating  impression  or  "bite"  and 
model — Combination  plaster  and  metal  model — Copper  amalgam  models. 

CHAPTER  V 

Molds  and  Dies 28 

Tubes,  caps  and  trays — How  to  make  a  tube  quickly — Impression  for 

ix 


X  CONTENTS 

Page 
fusible  metal  die — Moldine — Casting  the  die^ — Counter-dies — Combina- 
tion lead  and  fusible-metal  counter-die — Amalgam  dies — Amalgam — The 
Swager-swaging. 

CHAPTER  VI 

Investments  and  Soldering S3 

Materials  principally  used  for  investments — Small  investments — Large 
investments — Asbestos — ^Method  of  investing- — Preparation  of  investment 
for  soldering — Heating  the  investment — Soldering  blocks — A  serviceable 
and  lasting  soldering  block — The  structure  of  flame — The  bunsen  flame — 
The  blowpipe  flame — -Blowpipe  and  method  of  using  it — Preparation, 
application  and  fusing  of  solder — Solder-pointer — Soldering  practice 
dummies  for  students — Open-flame  soldering — Union  by  sweating — 
Soldering  with  a  compound  blowpipe  flame— Annealing. 

CHAPTER  VII 

The  Casting  Process 43 

Inlay  wax — Formation  of  the  inlay  wax  model— Investment — Investment 
material — Heating  of  the  investment — Gold — Expansion  and  contrac- 
tion of  materials  and  metals — Casting  machines — Casting  process — ^Large 
castings — The  Schweitzer  wax  sprue  former — Exit  vent — ^Large  wax 
models — To  insure  against  distortion  of  the  wax  model — To  cast  with  a 
swager. 

CHAPTER  VIII 

Finishing  Process 55 

Finishing  and  polishing — Electro-plating. 


PART  II 

Preparatory  Treatment  or  Teeth  and  Roots  for  Crown-  and  Bridge- 
work 59 

General  Consideration 61 

CHAPTER  I 

The  Pulps  op  Teeth 63 

Preparatory  processes — Disinfection  of  vital  dentin. 

CHAPTER  II 

Devitalization  of  the  Pulp 68 

Instantaneous   devitalization — -Use   of  cocain,  cataphoresis  and  pressure 


CONTENTS  xi 

Page 
anesthesia — Excision  of  the  crown  and  instantaneous  extirpation  of  the 
pulp — Devitalization  with  arsenic — When  devitalization  is  necessary  in 
preparation  for  crown-work  two  methods  are  practiced:  the  heroic — In- 
stantaneous devitalization — and  gradual  devitalization  by  arsenical 
treatment. 

CHAPTER  III 

PuLPLESS  Teeth 72 

Requirements  of  treatment — Preparation  of  root-canals — Reaming — 
Treatment — Use  of  antiseptics — Closure  of  the  apical  foramen  and  fill- 
ing of  the  canal. 

CHAPTER  IV 

Chronic  Alveolar  Abscess 89 

The  usual  forms^ — Abscess  of  the  first  form — Abscess  of  the  second  form 
— Exostosis — Third  form,  blind  abscess — Alveolarotomy — Granuloma — 
Apicoectomy,  amputation  of  the  apex  of  a  root — Hydrogen  peroxid — Prog- 
nosis of  chronic  alveolar  abscess  and  apicoectomy — Perforation  of  a  side 
wall  of  a  root-canal  or  of  the  dentin  at  the  bifurcation  of  the  roots. 


PART  III 
ARTIFICIAL  CROWN- WORK 

CHAPTER  I 

Artificial  Crown-work loi 

First  authentic  account  of  artificial  crowns  or  pivot  teeth- — The  first  por- 
celain pivot  teeth — Gold  pivot  teeth — First  porcelain  and  gold  pivot  tooth 
or  crown- — The  Richmond  porcelain  and  gold  collar  crown — The  earlier 
operations — The  Morrison  and  Beers  gold  crown — The  Foster  and  Law- 
rence crowns — The  Mack  and  Howland-Perry  crowns — The  Gates-Bonwill  . 
crown — The  How  crown — The  Weston  crown — The  Brown  crown — The 
new  Richmond  porcelain  crown — The  Logan  crown — Advantages  conferred 
by  improvements  in  cements — Classification  of  modern  crown-work. 

CHAPTER  II 

Principles  Involved  IN  Crown-work  . 108 

Nomenclature  of  crown-work — The  object  of  crowning  operations — The 
subject  of  occlusion — Malformed  occlusal  surfaces — Median  line  of 
natural  crown  and  root — The  post  in  relation  to  canals  and  roots — The 
post  in  relation  to  post  or  Dowel  crowns^ — Short  and  long  crowns — Princi- 
ples governing  the  construction  of  root-caps  without  collars — Posts  in  re- 
lation to  crowns — Selection  of  porcelain  teeth^ — Dependence  of  crown-work 
operations  on  asepsis. 


xii  CONTENTS 

CHAPTER  III 

Page 

Shaping  Teeth  and  Roots  for  Crown-work 119 

Local  anesthesia — Adrenalin  and  cocain — Instruments  used — Crowns 
without  collars  and  ready-made  porcelain  crowns — Collar  crowns — Princi- 
ples involved — Preparation  of  teeth  or  roots  for  all-gold  collar  crowns — 
Collar  crowns  with  porcelain  facings — Partial  collar  crowns — Special  prepa- 
ration of  badly  decayed  teeth  or  roots — Restoration  with  gold. 

CHAPTER  IV 

All-porcelain  Post  Crowns 132 

All-porcelain  detached-post  crowns — Preparation  of  the  root  end — The 
S.  S.  White  detached-post  crown — Preparation  of  the  root — Direct  method 
of  fitting  the  crown — Indirect  method — The  Davis  crown — The  Justi 
shoulder  pin  crown — Ash's  tube  teeth  and  crowns — Examination  of  the 
periphery  of  a  porcelain  post  crown — Removal  of  excess  of  porcelain  at 
the  periphery^ — Cementation — Remarks  on  the  use  of  ready-made  por- 
celain crowns  and  crowns  without  collars. 

CHAPTER  V 

Porcelain-post  Crowns  with  Metallic  Base 141 

Porcelain  detached  post  crown  with  cast  base — Direct  method — Indirect 
method — Porcelain  faced  gold  post  crown — Root  end  below  gum  margin. 

CHAPTER  VI 
A  Temporary  Crown 145 

CHAPTER  VII 

Gold  Collar  Crowns 146 

Construction  and  adaptation  of  collars — To  measure  the  circumference  of 
a  root  or  tooth — The  dentimeter — To  determine  the  width  of  a  collar — 
Cutting  the  plate  for  the  collar — To  solder  the  joint  of  the  collar — Sweating 
method — Fitting  a  collar  to  root  or  tooth — Platinum  collar — Reinforced 
thin  platinum  collar — Platinum-lined  gold-plate  collar — Application  of  a 
local  anesthetic — Collar  crowns  hygienically  considered. 

CHAPTER  VIII 

-LL-GOLD  Collar  Crowns  for  Bicuspids  and  Molars  Constructed  in 

Sections 156 

Methods  of  knuckling  the  collar  and  giving  contour — Methods  of  forming 
the  cusp-cap — Class  A,  dies — Method  No.  i — Swaging  the  cusp-cap — 
Stamping  the  cusp-cap  in  a  swager — Reinforcement  of  the  cusp-cap — Fit- 


CONTENTS  xiii 

Page 
ting  cusp-cap  to  collar — Soldering  cusp-cap  to  collar — Swaged  cusp-cap 
— Reinforced  with  22-carat  gold — Sweating — To  unite  by  sweating — 
Method  No.  2,  hollow  cusps^ — ^Class  B,  intaglio  or  depressed  dies — Method 
No.  3 — Method  No.  4,  cusp  buttons — Application — To  enlarge  a  cusp  button 
— Method  No.  s,  intaglio  die  from  wax  model — Intaglio  die-plate — Class 
C,  casting — Method  No.  fr — Solid  gold  cusp-cap — Special  method — Method 
No.  7 — Solid  gold  cusp-cap  by  soldering — Method  No.  8 — All-gold  crowns 
for — Incisors  and  cuspids — Cases  of  abrasion. 

CHAPTER  IX 

Gold  Collar  Crowns  with  Porcelain  Facings 174 

Incisors  and  cuspids — Adaptation  of  the  collar — To  form  floor  of  the  collar 
- — Indirect  method — Preparation  of  canal  to  receive  post — Posts — Union 
of  post  and  cap — Selection  and  adaptation  of  the  porcelain  facing — To  pro- 
tect the  incisal  edge  of  the  porcelain  facing — Backing  the  porcelain  facing 
— One  piece  backing — Pointed-pin  facings — Use  of  swager — Preparation  for 
investment — Investment — Soldering  and  finishing — Diversity  of  con- 
struction— Method  of  forming  posts  to  fit  canals  accurately — Hollow  posts 
— Construction — To  separately  back  or  veneer  the  base  of  a  porcelain 
facing  with  platinum — Two-piece  backing — Reinforced  backing. 

CHAPTER  X  ^ 

Gold  Collar  Crowns  with  Porcelain  Facings,  Continued 188 

Bicuspids  and  molars^ — To  form  a  cusp-cap — Inlaying  procelain  facings  in 
gold  crowns — Application  to  a  seamless  gold  crown — inlaying  porcelain 
facings  in  sectional  crowns — A  faulty  method — Crowning  in  cases  of 
abrasion — Gold  crowns  with  porcelain  facings  for  teeth  with  vital  pulps. 

CHAPTER  XI 

The  Gold  Seamless  Cap-crown  System 194 

Seamless  root-caps  for  incisor,  cuspid  and  bicuspid  crowns  with  porcelain 
facings — Impressions  and  dies — Method  of  stamping  seamless  metal  caps — 
All-gold  seamless  bicuspids  and  molars — All-gold  seamless  incisors  and 
cuspids. 

CHAPTER  XII 

Imparting  Contour  to  Seamless  Gold  Crowns 199 

Crowns  swaged  on  dies — Method  of  slitting  and  contracting  the  neck — 
Use  of  contouring  pliers — External  application  of  contour — To  contour 
on  the  die  with  a  swager — Sectional  mold  method — Formation — Shaping 
the  cap. 

CHAPTER  XIII 

Adjustment  of  Seamless  Gold  Crowns    .    .    .    .  ' 203 

Expansion  of  the  collar  and  crown — Alteration  of  a  side  or  part  of  a  crown 


XIV  CONTENTS 

Page 
—Alteration  of  the  occlusal  surface — To  deepen  the  cusps — To  point, 
lengthen  or  narrow  the  buccal  cusp  in  appearance — To  lessen  or  remove 
the  indentation  between  cusps — Strengthening  and  reinforcement  of  seam- 
less gold  crowns^ — Method  of  forming  a  solid  occlusal  surface — External 
reinforcement  v\'ith  platinum  and  gold  in  close  "bites" — Seamless  solid 
gold  dummies — Altering  a  seamless  gold  crown  to  the  form  of  a  corre- 
sponding natural  crown^ — Comparative  merits  of  the  sectional  and  seam- 
less methods  of  constructing  gold  crowns. 

CHAPTER  XIV 

Cast  Gold  Root-caps  and  Crowns 208 

Cast  root-cap— Cast  gold  crown  with  platinum  collar — Cast  gold  crown 
on  a  sectional  platinum  or  seamless  gold  cap. 

CHAPTER  XV 

Various  Forms  of  Porcelain-faced  Gold  Crowns 210 

Cup-shaped  cap — The  V-shaped  cap — Partial  collar  crowns — The  Litch 
crown. 

CHAPTER  XVI 

Porcelain  Detached  Post  Collar  Crowns 213 

Porcelain  detached  post  collar.  S.  S.  White,  Davis,  Ash  and  Justi  crowns 
— Attachment  of  a  porcelain  crown  with  a  metallic  base  backing — The 
Goslee  crown — Construction — Diatoric  porcelain  tooth  crown-^Cast  base 
for  detached-post  crown — Allow^ance  for  contraction. 

CHAPTER  XVII 

Partial  Crown-work 218 

Restoration  with  inlays^ — History- — Merits — Criticism^ — Impartially  con- 
sidered— Preparatory  treatment  in  inlay  work — Principles  governing  the 
preparation  of  cavities — Anchorage — Preparation  of  cavities — Gold  inlays 
— ^Labial,  buccal  and  occlusal  cavities — -Approximal  cavities — Compound 
cavities. 

CHAPTER  XVIII 

Partial  Crown-work,  Continued 228 

Gold  inlay  formation — Direct  method — Pin  anchorage  for  gold 
inlays — Hollowing  of  gold  inlays — Matrix  gold  inlays — Process  of 
formation — Solid  gold  tips  for  abraded  pulpless  anterior  teeth — The  cast- 
ingmethod — Cases  of  vital  pulps. 

CHAPTER  XIX 

Partial  Crown-work,  Continued   .    .    : ! 236 

Indirect  method  of  formation  of  inlays — Comparative  merits — Impression 


CONTENTS  XV 

Page 
materials — Process — Impression  tubes,  caps  and  trays — Formation  of  tubes 
and  caps — Method  of  forming  trays  and  taking  impressions — Inlay  dies — 
Indirect  inlay  wax  model  formation — Metallic  matrices,  indirect  method. 

CHAPTER  XX 

Special  Operations  in  Crown- work 249 

Crowning  molar  roots  decayed  apart  at  the  bifurcation — Cantilever  crown 
— Method  of  construction — Methods  of  crowning  in  cases  of  irregularity. 

CHAPTER  XXI 

Treatment  by  Cro'wn-work  of  Fractured  Teeth  and  Roots 252 

Fractured  crowns  and  roots — Longitudinal  fractures — Slanting  fractures 
— Inlay  casting  method — Use  of  a  cast  of  a  fractured  portion- — Amalgam — 
Post  and  amalgam. 

CHAPTER  XXII 

Processes  Connected  with  Crown-  and  Bridge- work 256 

Correction  of  excess  of  solder — To  securely  attach  a  crown — Importance 
of  removal  of  flux  from  interior  of  crowns — Correction  of  interfering  points 
in  adjustment  and  occlusion. 

CHAPTER  XXIII 

Cementation  of  Crown-  and  Bridge- work 258 

Zinc  oxyphosphate- — Method  of  mixing — Application — Gutta-percha — 
Method  of  cementing  with  gutta-percha  or  gutta-percha  cement — Method 
of  measuring  gutta-percha^ — To  apply  gutta-percha  in  the  form  of  a  film 
over  a  surface — To  cement  t!he  crown  or  bridge — For  temporary  inser- 
tion— Requirements  for  success— Oxyphosphate  in  combination  with 
gutta-percha  or  gutta-percha  cement — Silicate  cement — Amalgam. 


PART  IV 

BRIDGE-WORK 

INTRODUCTION 

Scientific  Mechanical  Principles 269 

Scientific  mechanical  principles — Dental  bridge-work — Antiquity— Primi- 
tive methods^ — Modern  literature — Modern  methods — Advantages — Ob- 
jectionable features — Prophylaxis — Impartial  consideration — Forms  of 
bridge  construction. 

CHAPTER  I 

Construction  of  Bridge-work 274 

Principles  involved — Abutments,  retentive  and  supporting — Occlusion — 


XVI  CONTENTS 

Page 
The  artistic  and  esthetic — Porcelain  facings  and  teeth  for  dummies — Clas- 
sification of  bridge-work — Preparation  of  the  supporting  teeth  or  abut- 
ments— Construction — Impressions  and  models — Selection  and  adjustment 
of  artificial  teeth — Backings — Occlusal  cusp-caps — Investing  the  bridge — 
Soldering — Finishing — Variations  in  method  of  construction- — Construc- 
tion in  sections — Soldering  on  the  model — Correction  of  warping — Adjust- 
ment and  insertion — Construction  of  bridge-woyk  embracing  both  sides 
of  the  mouth — Construction  of  small  pieces  of  bridge-work. 

CHAPTER  II 

Replaceable  Porcelain  Facings  and  Teeth 299 

Replaceable  ordinary  porcelain  facings  with  cast  box  backing — A  plate  box 
backing — Manufactured  replaceable  facings  and  teeth — The  Steele — The 
Ideal — The  Evslin — The  Stewart — The  Dimelow — Impa]:tially  considered. 

CHAPTER  III 

Forms  or  Attachments  for  Bridge-work 305 

Shoulders  on  superior  incisor  and  cuspid  crowns  or  dummies — Solid  gold 
dummies — Casting  method^ — Sectional  method- — Seamless  cap  method — 
All-gold  hollow  dummies — Anchorage  cavity  in  a  solid  gold  crown — An- 
chorage cavity  in  a  gold  cap-crown. 

CHAPTER  IV 

Attachments  for  Bridge- work  Continued, 309 

Open-face  crowns — Preparation  of  the  tooth — To  form  a  die — Seamless 
open-face  crown  construction^ — Open  face  sectional  crown- — Cementation 
of  open-face  crowns — Carmichael  attachment — The  Staple  attachment — 
MOD  and  MODL  or  Tinker  attachments — Shaping — Construction^ — Plate 
and  pin  attachments — Construction — Use  with  pulpless  teeth — Inlay  and 
bar  bridge-attachments — Inlay  attachments — Incisors  and  cuspids — 
Cavity  formation — Bicuspid  and  molars — Another  method- — Formation — 
Bar  attachment — Construction — Connecting  bars  for  bridges — Intervening 
roots. 

CHAPTER  V 

Bridge  Construction  on  Vital  Tooth  Abutments  and  Piers 321 

CHAPTER  VI 

Casting  Method 323 

Porcelain  crown  (detached-post)  bridge-work — Cast  sanitary  bridge — 
Sanitary  porcelain  and  gold  bridge — Extension  bridges — Mechanical 
principles  governing  construction — A  lug  support — Lug  anchor  with  lock- 
pin. 


CONTENTS  xvii 

CHAPTER  VII 

Page 

Extension  Bridges 328 

Governing  mechanical  principles — Construction — A  lug  support — A  lug 
anchor  with  lock-pin— Intervening  roots. 

CHAPTER  Vin 

Bridge-work  and  Splinting  in  Cases  of  Pyorrhea  Alveolars 333 

The  plate  and  pin  attachment — Use  of  connecting  collars — Posterior  teeth 
— Bicuspids  and  molars. 

CHAPTER  IX 

Repair  OF  Crown- AND  Bridge- WORK 337 

The  ordinary  method — Dr.  Bryant's  method — Countersunk  pinhole 
method — To  repair  with  a  Dimelow  facing — Ash's  repair  facings — Inlay 
method — Repair  of  an  incisor  or  cuspid  gold-backed  crown  with  a  detached- 
post  crown — Silicate  cement — Advantages  of  detachable  bridge-work — Re- 
moval of  crowns  or  bridges  cemented  with  zinc  oxyphosphate — Removal  of 
a  post — A  post  puller — Difficult  post  removal — Removal  of  crowns  or 
bridges  cemented  with  gutta-percha,  alone  or  combined  with  oxyphos- 
phate— Repair  of  a  gold  collar  crown. 

CHAPTER  X 

General  Application  of  Fixed  Crown-  and  Bridge-work 347 

Central  or  lateral  incisors,  cuspids  or  bicuspids — Centrals,  laterals  or  cus- 
pids combined — cuspids,  bicuspids  and  molars  combined — Bicuspids  and 
molars  combined— Use  of  partial  cap — Incisors,  cuspids,  bicuspids  and 
molars  combined — Extensive  application  of  fixed  crown-  and  bridge- work — 
Criticism. 

CHAPTER  XI 

Sectional  and  Detachable  Bridge-work   .    ; 362 

Construction  in  sections — Bar  attachment- — Dovetail  lug  attachment — 
Detachable  double-cap  bicuspid  and  molar  crowns — Detachable  gold  sertii- 
circular  post  crowns. 

CHAPTER  XII 

Ti^E  Hygienic  Condition  of  the  Mouth  as  Affected  by  Fixed  Bridge- 
work  367 

Consideration  of  the  subject — Requirements — Method  for  cleanliness  and 
health. 


xviii  CONTENTS 

PART  V 

CHAPTER  I 

Page 

Removable  Bridge-work 371 

Limitations — Requirements — Examination  models — Forms  of  crowns,  at- 
tachments and  supports — Removable  retaining  abutments — Removable 
supporting  abutments — The  tube  and  split-post  attachment — Construction 
of  the  split  post — Split-post  swaging  device — Split-post  burnisher^ — Tele- 
scope crowns — The  outer  or  telescoping  cap — Contour — The  cusp-cap — 
Telescope  crown  with  tube  and  split-post — Removal  of  the  cap  from  the 
die — Tube  and  split-post  anterior  crowns — Incisors,  cuspids  and  bicuspids 
with  porcelain  facings — The  outer  cap — Converging  teeth  and  roots — 
Retaining  inlay  abutments — Bicuspids  and  molars — The  matrix  or  female 
inlay — Split-post  and  supplementary  or  male  inlay — A  pin  bender — Va- 
riations in  method — Incisors  and  cuspids — To  take  the  impression — Inser- 
tion of  the  split  post — The  supplementary  inlay — Use  of  swaged  first  or 
female  matrix — Supporting  abutments— Special  forms  of  attachments — 
Collar  and  partial  cap — Flanged  collar  attachment- — ^Lug  collar  support — 
Split-bar  attachment — Construction — The  split  bar — The  box — Paral- 
leling the  box— The  shield — Winged  lug  attachment — Split  winged  lug — 
Dove-tail  flange  and  split-post  attachment — Solid  pin  and  tube  attach- 
ment— Comparative  values  of  the  several  forms  of  attachment — Reten- 
tive attachments — Retentive  inlay  attachments — Supporting  attachments. 

CHAPTER  II 

Construction  of  Removable  Bridge-work 411 

Method  of  construction — The  paralleling  staple — Removable  bridge  ex- 
tending on  both  sides  of  the  mouth — Construction — Diversity  of  construc- 
tive details — Use  of  paralleling  instruments — The  Chayes  parallelometer. 

CHAPTER  III 

The  Split  Bar  Bridge 425 

CHAPTER  IV 

Removable  Saddle  Bridge-work 428 

Construction  of  saddles — Method  of  taking  impressions  for  saddles — The 
articulation — The  bridge  teeth — Construction  of  porcelain-faced  solid 
gold  dummies  for  saddles — Solid  gold  teeth  dummies — Vulcanite  attach- 
ment— Extension  saddle  bridge — An  adjustable  saddle — Vulcanite  exten- 
sion saddle. 

CHAPTER  V 

Removable  Plate  Bridge-work 441 

Merits — ^Limatations — Clasps  with  lugs — Preparation  for  clasp  attachments 


CONTENTS  XIX 

Page 
— Shaping  clasps — Collar  method — Cast  clasps— Clasps  and  lugs — Forma- 
tion of   inlay  lugs — Lugs  for  natural  crowns — Construction   of    a  plate 
bridge — Uniting  attachments  to  plate — To  correct  warping — A  frequent 
cause  of  warping. 

CHAPTER  VI 

General  Application  of  Removable  Bridge-work 456 

Centrals,  laterals  and  cuspids — Bicuspids  and  molars — Connecting  bars 
to  saddles — Cast  saddles  and  plates. 

CHAPTER  VII 

Manufactured  Attachments 463 

The  roach  attachment — Method  of  application — Construction  of  bridge — 
The  Morgan  attachment — ^Removable  bar-bridge  attachments — The  Gil- 
more  attachment — Split-bar  bridge  attachment — The  Chayes  method  and 
attachments — The  parallelometer — The  parallelodrill — The  attachments 
— The  bucco-lingual  attachment — The  upright  attachment — The  distal 
extension  attachment — Construction — Split-post  and  bar  attachment. 


PART  VI 
PORCELAIN  DENTAL  ART 

Introduction 481 

CHAPTER  I 

Porcelain  Compounds  or  Bodies 482 

Ingredients :  Their  chemical  and  physical  character — ^Low-  and  high-fusing 
porcelain  bodies — Coloring  of  porcelain  compounds — Gum  enamel — 
Foundation  or  basal  body — Preparations  of  porcelain  bodies — Selection  of 
the  color  of  the  porcelain  body — Sample  shades — Variation  in  shade — 
Stability  of  shade  in  use — Spatula  and  brushes  used — Preparation  of 
porcelain  body  for  use — Use  of  gum  tragacanth  or  starch — Application  of 
porcelain  body. 

CHAPTER  II 

Furnaces 488 

Electric — Gasoline — Gas — Use  of  furnaces — Advantages  of  the  electric 
furnaces — Dental  furnace  pyrometer. 

CHAPTER  III 

Fusing  of  Porcelain 492 

Importance  of  the  operation  of  fusing — Shrinkage — Baking  or  fusing — Re- 
quirements in  baking — First  bake — Second  bake — Final  bake — Cooling 


XX  CONTENTS 

Page 
and  annealing  or  tempering  of  porcelain — Diiiiculty  attending  the  proper 
fusion  of  small  masses  of  porcelain  body— Method  used  to  indicate  point 
of  fusion — Merits  of  a  pyrometer. 

CHAPTER  IV 

Staining  of  Porcelain 496 

Character  and  purpose  of  mineral  stains — Use  of  the  colors — -Application 
— Gradation  of  shade — Fusing. 


CHAPTER  V 

Character  and  Suitability  or  Low-  and  High-fusing  Porcelains  for  In- 
lay- AND  Crown-work 499 

Requirements — Comparative  merits — -Fusing  points  of  dental  porcelains 
— Suitable  application  of  each  grade, 

CHAPTER  VI 

Porcelain  Inlays 501 

The  earlier  methods — Modern  inlays  and  their  merits — Instruments  and 
materials  used  in  the  adaptation  of  matrices — Preparation  of  cavities- 
Direct  method — -Formation  of  matrices  for  low-fusing  porcelains — Re-  ■ 
moval  of  the  matrix — Investing  the  matrix  for  low-fusing  porcelain — 
Platinum  matrix  for  high-fusing  porcelain — To  facilitate  the  shaping  of  a 
matrix — Indirect  method — Process  of  shaping  a  matrix  by  a  mold  or  die — 
Removal  of  the  matrix — Application  of  porcelain  body — The  Jenkins  low- 
fusing  body — Use  of  electric  furnace  for  baking^ — Method  of  fusing — The 
application  of  high-fusing  porcelain  body — First  bake — Second  bake — 
Final  bake — Comparative  heat  of  the  final  bake — Removal  of  a  foil 
matrix — Preparation  for  cementation — Methods  of  etching  with  acid  or  a 
diamond — To  aid  adjustment  in  cementation — Cementation — Require- 
ments; effect  on  color  of  porcelain — Operation  of  cementation. 

CHAPTER  VII 

Special  Operations ■ 515 

Large  contour  inlays — Use  of  pieces  of  porcelain  teeth — Use  of  successive 
grades  of  bodies — Occlusion  in  close  "bite" — Porcelain  inlays  in  com- 
bination with  gold  or  amalgam  fillings — Atrophy  and  erosion^ — Porcelain 
tips — Porcelain  shoulders  preferable,  to  pins  for  retention — Wire  loop — 
Small  fractures — Preparation  of  the  cavity — The  rod  inlay — Cementation 
and  finishing — Points  to  bear  in  mind — To  facihtate  matrix  adaptation — 
Tray  to  bake  on — To  overcome  contraction  of  body— To  aid  removal  and 
remedy  tear  of  matrix — Advantages  of  the  use  of  a  foundation  body  in 
contour  operations — The  use  of  a  lens — Porosity  of  porcelain — Edges  of  in- 
lays— Small  inlays — Effect  of  cement  on  shade— Requirements  in  inlay- 
work — Conservative  limitations  of  porcelain  inlay-work. 


CONTENTS  xxi 

« 

CHAPTER  VIII 

Page 

Porcelain  and  Platinum  Crown-work 523 

Structural  requirements — Platinum  solder — Nature  of  adhesion  of  porce- 
lain fused  on  platinum — Application  of  porcelain  body  in  cxown-work — 
Baking — Degrees  of  heat — Porcelain  and  platinum  collar  or  partial  collar 
crowns — Process  of  construction  of  collar  crown — Partial  collar-cap — Bi- 
cuspids and  molars — Practical  method  to  form  occluding  section — Crown 
without  a  collar — Limitations — Jacket  crown — Incisors  and  cuspids  with 
platinum  jacket — Application  of  porcelain  veneer — Protection  of  the  in- 
cisal  edge — Porcelain  and  platinum  bicuspid  cap-crown  with  porcelain 
occlusal  surface — Porcelain  and  platinum  tube  crown — A  porcelain  and 
platinum  bicuspid  crown  with  metal  occlusal  surface— Porcelain  and 
platinum  tube  crown — x\pplication  to  cases  of  fractured  porcelain  crowns 
— Ready-made  crowns  on  capped  roots — The  S.  S.  White,  Davis,  Ash  or 
Justi  crown  on  a  capped  root — All-porcelain  jacket  crown — Application  of 
veneer  and  porcelain  to  cone — To  form  a  veneer — Formation  of  porcelain 
crown  without  a  veneer — Removal  of  matrix  or  cone — Cementation — The 
overlap  crown — Crowning  of  roots  decayed  apart  at  the  bifurcation — 
Comments  on  grades  of  porcelain — Compounding  artificial  tooth  body. 


PART  VII 

CROWN-,  BRIDGE-  AND  PORCELAIN-WORK  COMBINED 
WITH  OPERATIVE  DENTISTRY  IN  DENTAL  PROSTHESIS 


CHAPTER  I 

Operations  in  Dental  Prosthesis 545 

Symmetrjr — Cases  showing  the  results  of  combined  operations — Gold  and 
porcelain  sanitary  bridge — Combined  root  and  crown  replacement  with 
porcelain — Inlay  restoration  in  a  close  incisal  occlusion. 


INTRODUCTION  TO  EIGHTH  EDITION 


Or  the  origin  of  the  art  of  dentistry  no  one  can  speak  with  certanity, 
as  its  early  history  is  'shrouded  in  the  mists  of  antiquity;  but  dental 
operations  are  recorded  in  very  remote  times. 

References  are  made  to  the  art  in  the  writings  of  Hippocrates,  in 
the  fifth  century  B.C.  Martial,  the  Latin  poet,  in  the  first  century  B.C., 
says  of  a  Roman  dentist,  "Cascellius  is  in  the  habit  of  fastening  as 
well  as  extracting  the  teeth."  To  Lelius  he  says,  "  You  are  not  ashamed 
to  purchase  teeth  and  hair;"  and  adds  that  "the  toothless  mouth  of 
Egle  was  repaired  with  bone  and  ivory;"  also,  that  "  Galla,  more  refined, 
removed  her  artificial  teeth  during  the  night." 

Horace,  in  the  same  century,  cites  the  case  of  the  "sorceresses 
Canidia  and  Sagana  running  through  the  city  and  losing  the  one  her 
false  hair,  the  other  her  false  teeth." 

Galen,  the  celebrated  physician,  in  the  second  century  a.d.,  also 
speaks  of  the  art  of  dentistry  as  being  then  practiced. 

These  early  operations  were  limited  to  the  extraction  of  offending 
teeth  and  the  replacement  of  those  which  had  been  lost  with  substitutes 
that  were  retained  in  position  by  means  of  narrow  bands  or  ligatures 
attaching  them  to  the  adjoining  natural  teeth,  and  without  the  use 
of  plates.  Crude  as  they  were,  they  formed  the  first  expression  of  the 
art  of  dentistry,  a  beneficent  art  from  the  beginning,  in  that  it  sought  to 
remedy  pathological  or  accidental  defects.  Confined  to  the  simplest 
operations,  it  existed  for  centuries,  and  then  was  apparently  lost  during 
the  Dark  Ages,  to  reappear  when  the  more  general  diffusion  of  knowledge 
ushered  in  the  modern  era  of  science  and  invention. 

After  its  revival,  dentistry,  so  much  of  it  as  was  known,  was  in  a 
measure  a  secret  art,  the  practice  of  which  even  within  the  memory  of 
men  now  living,  was  involved  in  mystery;  but  recent  progress  has  lifted 
the  veil,  and  dentistry,  in  the  treatment  of  the  teeth  on  correct,  scien- 
tific, rational  principles,  has  developed  an  art  and  a  science  which  have 
given  it  honorable  rank  among  the  professions.  In  its  twofold  evolu- 
tion it  has  absorbed  from  every  available  source  whatever  would 
broaden  its  science  or  perfect  its  art.  It  calls  to  its  aid  anatomy, 
physiology,  pathology,  chemistry,  therapeutics,  metallurgy,  sculpture, 


xxiv  INTRODUCTION   TO  EIGHTH  EDITION 

and  mechanics,  with  each  of  which  it  stands  in  closer  or  more  remote 
relation;  and  the  practitioners  of  dentistry  who  have  become  the  most 
eminent  and  useful  have  been  men  of  broad  attainments  and  great 
versatility  of  talent. 

In  the  history  of  all  progress,  movements  apparently  of  a  more  or 
less  reactionary  character  are  recorded.  In  the  useful  arts  especially  it 
is  not  uncommon  to  find  a  return  to  forms  and  methods  formerly  used, 
but  long  since  discarded  and  forgotten.  So  in  dentistry  we  find 
methods  of  treatment  and  modes  of  practice  once  in  vogue  but  long 
fallen  into  disuse,  revived  with  improvements  and  modifications  that 
stamp  them  as  practically  rediscoveries. 

These  movements  are  not  to  be  regarded  as  retrogressive,  because 
the  modifications  which  accompany  the  reintroduction  of  practical 
ideas  and  inventions  attest  them  as  real  advances,  and  indicate  clearly 
that  the  cycle  of  knowledge  is  ever  widening  with  experience.  This 
volume  demonstrates  how  modern  dentistry  has  utilized  the  principles 
of  some  of  the  simplest  original  oserations,  and  by  "proving  all  things, 
holding  fast  that  which  is  good,"  has  attained  its  present  honorable 
position  in  both  its  scientific  and  artistic  departments. 

The  history  of  dentistry  of  later  years  is,  in  brief,  a  recital  of  progress 
and  improvement.  The  medical  profession,  recognizing  the  rela- 
tionship prophylaxis  of  the  mouth  bears  to  the  general  health  and  the 
important  sphere  in  oral  surgery  and  prosthesis  dentistry  filled  in 
the  late  European  war,  accepts  dentistry  as  a  profession,  an  adjunct 
to  their  own.  The  United  States  Government  so  estimates  the 
services  of  the  dental  profession  in  the  Army  and  Navy  as  to  commission 
members  in  the  service. 

Such  is  the  position  which  dentistry  has  attained.  Much  of  the 
progress  which  has  made  its  present  elevation  possible  must  be  credited 
to  the  dental  profession  of  the  United  States,  which  has  been  justly 
termed  the  cradle  of  modern  dentistry.  Here  the  validity  of  the  idea 
that  scientific  knowledge  should  form  the  basis  of  training  for  prac- 
tice was  first  demonstrated  by  the  successful  establishment  of  dental 
schools;  here  the  first  journal  for  the  interchange  among  dentists  of 
thought  and  experience  was  founded;  here  the  first  association  having 
for  its  object  the  uplifting  and  upholding  of  dentistry  by  the  mutual 
helpfulness  of  its  practitioners  had  its  origin;  here,  in  a  word,  dentistry 
was  first  divorced  from  mystery,  here  it  first  passed  the  narrow  con- 
fines of  a  mere  handicraft  and  earned  for  itself  the  right  to  be  classed 
among  the  learned  and  liberal  professions. 


ARTIFICIAL  CROWN-  AND  BRIDGE-WORK 


Modern  artificial  crown-  and  bridge-work  belongs  to  the  depart- 
ment of  dentistry  formerly  termed  "mechanical;"  but  the  judgment, 
skill,  and  scientific  information  required  in  the  selection  and  treat- 
ment of  teeth  and  roots,  associates  it  with  operative  dentistry. 

Modern  crown-  and  bridge- work,  properly  understood  and  properly 
performed,  takes  high  rank  in  dental  art,  and  offers  wide  scope  for  ver- 
satiHty  of  talent  and  inventive  genius.  The  varied  and  complicated 
cases  presenting  for  treatment  frequently  suggest  to  the  expert  novel 
contrivances  and  methods  of  construction  and  application.  Successful 
practice  of  crown-  and  bridge-work  depends  upon  a  thorough  mastery 
of  the  underlying  principles  and  expertness  in  the  processes  involved, 
governed  by  sound  judgment  and  perfect  candor.  The  interests  of 
the  patient  should  be  paramount  to  every  other  consideration,  and  after 
a  careful  examination  he  should  be  given  an  accurate  statement  of  the 
applicability  of  the  system  to  this  case,  in  respect  to  usefulness,  appear- 
ance, durability,  and  comfort,  as  compared  with  other  processes  and 
appliances  in  use. 

Surgical  and  mechanical  operations  of  the  most  delicate  nature  are 
required.  Nothing,  indeed,  in  dentistry  demands  finer  manipulation. 
A  practical  consideration  of  the  subject  will  show  that  a  knowledge  of 
anatomy,  pathology,  and  therapeutics,  and  as  well  mechanical  and 
artistic  skill,  are  necessary  to  the  correct  treatment  of  cases  and  the 
proper  performance  of  the  operations  indicated.  Among  the  principal 
steps  in  an  operation  may  be  named,  first,  the  preparatory  treatment  of 
the  natural  roots  and  teeth  for  the  final  process,  involving  the  diagnosis 
of  present  or  probable  lesions  and  the  prescription  of  whatever  remedial 
or  prophylactic  measures  may  be  needful;  second,  in  crown- work,  the 
adaptation  of  the  artificial  crowns  to  the  cervical  portion  of  the  natural 
roots  and  the  contiguous  membranes,  and  the  restoration  of  the  articu- 
lation and  the  anatomical  contour;  and,  in  bridge-work,  the  selection  of 
suitable  teeth  or  roots  for  foundation  piers  or  abutments,  and  the  choice 
and  adaptation  in  constructive  practice  of  the  forms  which  will  insure 
the  highest  degree  of  stability  and  best  sustain  the  force  of  occlusion, 
thereby  avoiding  abnormal  positions  and  conditions. 


XXVI  ARTIFICIAL   CROWN-  AND  BRIDGE-WORK 

In  no  branch  of  dentistry  will  lack  of  knowledge  and  skill  or  the 
exhibition  of  carelessness  in  constructive  details  be  more  plainly  evi- 
denced or  result  in  greater  proportion  of  injury  instead  of  benefit. 
Many  failures  are  to  be  attributed  to  attempts  to  perform  bridge-work 
operations  with  about  the  same  expenditure  of  time  on  the  part  of  the 
dentist  and  of  money  on  the  part  of  the  patient  as  in  plate- work.  There 
is  no  such  relationship  between  these  two  methods  of  procedure. 

The  practice  of  crown-  and  bridge-work  by  dentists  possessing  the 
requisite  attainments  and  governed  by  correct  ethical  principles  gives 
results  which  have  gradually  estabHshed  its  value,  removing  erroneous 
impressions  and  insuring  a  wide  professional  and  public  indorsement 
of  this  important  branch  of  prosthetic  dentistry.  Its  extraordinary 
facilities  for  preserving  and  replacing  teeth  have  made  for  it  a  high  posi- 
tion in  dental  art. 


PART  I 

MATERIALS  AND  PROCESSES  USED  IN 
CROWN-  AND  BRIDGE- WORK 


CHAPTER  I 

PREPARATORY  REQUIREMENTS 

INSTRUMENTS — TOOLS — PRECIOUS    METALS — BASE    METALS — MATERIALS 

AND   ACCESSORIES 

A  complete  equipment  for  crown-  and  bridge- work,  as  will  be  seen 
from  the  list  following,  embraces,  besides  many  instruments,  materials 
and  appliances  both  from  the  operative  outfit  of  the  practicing  dentist 
and  the  dental  laboratory.  Not  all  of  these  are  necessary  for  the 
beginner,  but  he  will  find,  as  he  advances,  that  all  of  them  will  be 
required  in  the  work  itself  or  the  preparatory  surgical  procedures. 

Instruments 

Swiss  and  Donaldson  broaches. 

Kerr's  Pulp-Canal  Files  and  Reamers. 

Gates-Glidden  drills — all  sizes,  straight  and  for  right-angle  attach- 
ment. 

Root-ca-roal  probes  and  pluggers. 

Root-canal  reamers,  Peeso's. 

Enamel  O.  S.  cleavers  (Orton's). 

Root  shapers — cross-cut  cone-shaped  trimmers  (Evans)  See  Part 
III,  Chapter  III. 

Root  facers,  Nos.  7-8-9. 

Carborundum  wheels,  disks  and  points.     See  Part  III,  Chapter  III. 

Tools 

Pliers  for  shaping  collars — Peeso  No.  118,  Robinson  No.  120, 
contouring  No.  130.     See  part  III,  Chapters  VI  and  VII. 

Pin  roughening  and  bending  pliers,  No.  127. 

Cutting  pliers. 

Small  pointed  shears,  straight  and  curved,  Nos.  10  and  11.  See 
Part  III,  Chapter  VIII. 

Plate  burnisher  No.  i. 

Pin  vise  No.  4. 

Small  anvil.     See  Part  III,  Chapter  VI. 

Hammer-headed  hand-vise — %  inch  jaw. 

Tweezers  C,  N,  0,  L. 

Solder  tongs. 


4  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

One  round  file,  fine. 

Two  half-round  files,  3  in.  No.  6  cut,  and  5  in.  No.  2  cut. 
Two  flat  files,  5  in.  No.  2  cut,  5  in.  No.  6  cut,  one  side  smooth. 
Bunsen  burner  with  spider — ^See  Part  I,  Chapter  VII. 
Asbestos  soldering  block — See  Part  I,  Chapter  VII. 
Charcoal  soldering  block — See  Part  I,  Chapter  VII. 
Blowpipe — ^Lee  or  Melotte. 

Ladle  for  melting  fusible  metal — See  Part  I,  Chapter  III. 
Small  impression  cups — See  Part  I,  Chapter  IV. 
Small  articulators — See  Part  I,  Chapter  IV. 
Gage  plate  Standard  Wire-gage  (Brown  and  Sharpe). 
Crown  swager  with  steel  blank  and  rubber  plunger  (S.  S.  White) 
and  Peeso's  swaging  device  No.  2  for  flattening  plate. 
Die-plate  for  forming  occlusal  cusps. 
Cusp  buttons,  and  assortment  of.     See  Part  III,  Chapter  VII. 

Precious  Metals 

Pure  gold  plate,  Nos.  28  to  34  gage,  and  No.  40  gage  to  form  matrices 
for  occlusal  cusps. 

Gold  plate,  22-carat,  Nos.  28  to  30  gage. 

Gold  clasp,  No.  24  gage. 

Platinized  gold  wire,  round,  Nos.  12,  14,  16,  18,  and  20. 

Platinized  gold  wire,  half  round,  Nos.  12,  13,  and  14. 

18-  and  20-carat  solder;  also  hard-flowing  solder. 

Platinum  plate.     Nos.  32  to  40  gage  for  collars  and  backings. 

Platinum  foil,  Kooo  and  ^^ooo- 

Iridio-platinum  wire,  Nos.  15  and  17  gage  for  posts  and  Nos.  19,  20 
and  21  gage  for  pins  in  either  gold  tips,  inlays  or  crowns. 

A  few  dwts.  of  silver  solder  for  special  purposes. 

Porcelain  teeth;  a  small  assortment  of  cross-pin  plate  teeth  (fac- 
ings) of  light,  medium  and  dark  shades,  consisting  of  incisor,  cuspid, 
bicuspid  and  molar  forms,  is  very  convenient  to  have  on  hand. 

Base  Metals 

Fusible  metal. 

Amalgam  for  models. 

Sheet  copper,  Nos.  30  to-  38  gage. 

Spool  each  of  iron  and  copper  wire  No.  31  gage  for  measuring. 

Iron  wire  about  No.  17  to  18  gage  for  encircHng  investments  and 
other  purposes. 

German  silver  plate  or  platinoid,  No  30  gage,  and  wire  No.  12  to 
20  gage. 


PREPARATORY  REQUIREMENTS  5 

Materials  and  Accessories 

Impression  compound. 

Impression  compound  in  sticks. 

Wax,  stiff,  in  sheets. 

Sticky  wax. 

Inlay  wax. 

Finely  ground  silex  or  calcined  marble-dust. 

Moldine.i 

A  small  rolling-mill  for  plate  will  be  quite  an  acquisition,  as  gold 
scraps  can  be  remelted  and  formed  into  plate,  and  plate  on  hand 
can  be  reduced  to  any  desired  gage. 


Fig.   I. 


Pig.  2. 


For  porcelain  work  an  outfit  of  high  or  low-fusing  porcelain  body, 
or  both,  to  be  used  for  inlay  or  crown  work.    (See  Part  VI,  Chapter  I.) 

Six  plug-finishing  burs  Nos.  B,  C,  D,  200,  201,  and  246. 

Two  inlay  burs  Nos.  i  and  2. 

Three  camePs-hair  brushes — small,  medium  and  large. 

One  gem  cavity  trimmer  No.  5. 

A  double  end  spatula  for  porcelain  work.     (Capon.) 

Several  fire-clay  slabs  for  holding  the  work  while  baking. 

Pulverized  silex. 

A  set  of  suitable  burnishers  for  adaptation  of  matrices,  long  handles, 
Nos.  25,  26,  27,  and  28. 

Locking  tweezers  "K. " 

1  Introduced  by  Dr.  G.  W.  Mclotte. 


6  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

An  electric  furnace,  preferably  with  a  pyrometer. 

A  bench  on  which  the  principal  parts  of  the  work  are  done  should 
be  especially  designed  and  reserved  for  it.  It  may  be  in  the  same  room, 
conveniently  situated  a  little  behind  the  dental  chair  out  of  view  of  the 
patient  or  located  nearby  in  an  adjoining  room.  Everything  connected 
with  the  bench  should  be  kept  in  order  and  ready  for  immediate  use. 
Such  a  bench  of  oak  or  mahogany  with  a  top  that  can  be  closed  when 
not  in  use,  making  an  unobjectionable  piece  of  furniture,  is  represented 
in  Figs.  I  and  2. 

The  Bunsen  flame  in  the  center  of  the  bench  can  be  turned  off  and 
relighted  instantly  by  a  small  jet  at  the  side  of  the  burner.  The  joint 
of  the  socket  of  the  gas  bracket  is  formed  so  that  when  the  bracket  is 
pushed  to  one  side  for  the  purpose  of  closing  the  cover  of  the  bench, 
the  gas  supply  is  shut  off.  Large  and  small  soldering  with  the  regular 
gas  blowpipe  may  be  done  at  this  bench;  also  soldering  by  the  open 
flame;  but  the  laboratory  is  a  more  suitable  place  for  the  former,  as  the 
smoke  emanating  from  a  blowpipe  will  gradually  soil  the  adjacent  walls 
and  ceiling. 

A  small  electric  lathe-head  can  be  mounted  on  the  bench. 


CHAPTER  II 

PLATES  AND  SOLDERS' 

PLATINUM — PLATINUM  FOIL  AND  WIRE — PLATINUM  AND  GOLD  FOR 
COLLARS — IRIDIUM — GOLD — GOLD  ALLOYS — FORMULAS  FOR  CROWN- 
WORK — CLASP  GOLD — GOLD  PLATINUM-LINED  PLATE — PLATINIZED 
GOLD — MELTING  AND  REFINING  OF  GOLD  SCRAPS — GOLD  SOLDERS — 
HARD  GOLD  SOLDER  — PEESO  FORMULAS — FLUXED  SOLDER  FILINGS — 
PLATINUM  SOLDER — SILVER  SOLDER — FLUX — JEWELER's  LIQUID 
FLUX 

In  the  construction  of  crown-  and  bridge-work,  gold  and  platinum 
are  used  pure  and  alloyed  with  other  metals  of  the  platinum  group, 
or  with  silver  and  copper  as  best  suits  the  requirements  of  the  work  and 
the  preference  of  the  dentist. 

Platinum. — Platinum  retains  its  color  and  resists  the  action  of  the 
secretions  of  the  mouth  better  than  pure  gold.  For  this  reason  and 
also  because  of  its  physical  properties  respecting  malleability  and  duc- 
tility, as  well  as  its  extremely  high  fusing-point  when  formed  in  any 
gage  of  plate  or  foil,  it  is  a  very  useful  material  in  many  departments  of 
the  work.  Platinum  is  also  valuable  as  an  alloy  to  raise  the  melting- 
point  of  gold  plate  and  increase  its  tensility. 

Platinum  plate  gages  Nos.  31  to  35  and  when  reinforced  with  pure 
gold  as  thin  as  No.  38  gage,  is  used  for  forming  collars  for  crowns. 

Platinum  FoU  and  Wire. — Platinum  in  the  form  of  thin  plate  from 
No.  40  gage  to  that  of  foil,  and  of  wire,  gages  No.  21  to  No.  14,  is  used 
in  various  operations  associated  with  the  work. 

Platinum  foil  can  be  made  exceedingly  thin  by  first  rolling  it  down 
to  about  i/iooo  of  an  inch,  annealing  in  an  electric  furnace,  then  oiling 
the  surface,  doubling  over  and  again  rolling  down.  Treated  by  this 
method  the  metal  is  less  liable  to  crack. 

Platinum  and  Gold  for  Collars. — In  some  cases  platinum  can  be 
utilized  to  advantage  for  making  collars  at  from  Nos.  36  to  38  gage.  The 
collar,  when  fitted,  is  stiffened  by  the  addition  of  pure  gold  melted  over 
its  outer  surface. 

1  The  subject  of  plates  and  solders  is  here  discussed  only  in  relation  to  crown- 
and  bridge-work  operations.  For  an  extensive  consideration  of  their  properties 
the  reader  is  referred  to  works  on  Metallurgy. 

7 


8  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Iridium. — Iridium  as  an  alloy  for  platinum  imparts  hardness  and 
elasticity.  The  usual  proportions  are  lo  per  cent,  iridium  and  90 
per  cent,  platinum.  Iridio-platinum  wire  of  the  same  gages  as  plati- 
num wire  for  the  same  purposes  is  employed  for  posts  and  pins  when 
greater  rigidity  is  required  than  pure  platinum  affords.  Palladium 
is  also  used  as  an  alloy  instead  of  iridium. 

Gold. — Gold  plate,  24  carats,  gages  No.  28  to  No.  36,  is  generally 
used  for  backing  porcelain  teeth  and  forming  collars  where  great 
flexibility  of  metal  is  required;  also,  as  thin  as  4/1000  inch,  cut  in  a 
strip  five-eighths  inch  wide,  when  to  be  stamped  up  as  a  cusp-cap  to 
act  as  a  matrix  for  coin  gold. 

The  plate  is  slightly  alloyed,  about  23  carats  fine,  for  crown-work 
when  a  less  flexible  metal  is  required;  gold  plate,  22  carats,  gages 
Nos.  29  to  31,  in  constructing  collars  for  crowns  with  porcelain  facings, 
all-gold  crowns  made  in  sections  and  seamless  crowns.  Gold  plate  of 
20  carats  is  also  used  in  the  construction  of  bridge-work. 

Gold  for  constructing  collars  should  be  of  as  high  a  carat  as  possible 
to  better  resist  the  action  of  acids.  A  large  proportion  of  copper  as  an 
alloy  is  objectionable,  owing  to  its  tendency  to  cause  tarnishing  of  the 
collar  when  an  acid  condition  of  the  mouth  exists. 

Gold  Alloys. — United  States  gold  coin  is  much  used  in  crown-  and 
bridge- work,  owing  to  its  flexibility,  strength  and  the  fine  finish  of 
which  it  admits.  As  it  contains  10  per  cent,  of  copper,  it  is  not  as  well 
able  to  resist  oxidation  in  the  mouth  as  some  other  alloys  that  closely 
resemble  it  in  commendable  properties. 

Formulas  for  Crown-work 

The  following  is  the  author's  formula  for  gold  plate  for  crown- work: 

Pure  gold 36 

Platinum 3 

Coin  gold ,. 61 


100  parts 


The  platinum  and  pure  gold  should  be  melted  together  first,  rolled 
out  and  cut  into  small  pieces.  The  coin  gold  is  next  melted  and  the 
platinized  gold  added.  The  alloy  closely  resembles  coin  gold  in  color, 
flexibility  and  strength.  It  is  much  higher  fusing,  the  joints  of  collars 
and  crowns  made  of  it  can  be  soldered  with  coin  gold  and  it  will  permit 
the  use  of  high-grade  solders  with  less  risk  of  fusing  the  parts  than 
when  coin  gold  or  ordinary  22-carat  plate  is  used. 


PLATES  AND  SOLDERS  9 

Clasp  Gold. — The  following  alloy  possesses  resiliency  and  is  of  good 
color: 

Pure  gold 20  dwt. 

Platinum 4  dwt. 

Silver 2  dwt.  20  grs. 

Copper I  dwt.  18  grs. 

The  above  formula  cannot  be  properly  fused  in  less  than  one  ounce 
lots.  The  platinum  must  be  thoroughly  alloyed  with  the  pure  gold 
before  the  addition  of  the  other  metals. 

Gold  Platinum-Lined  Plate. — Gold  plate  24  carats,  with  a  lining 
of  platinum,  can  be  used  in  any  of  the  processes  of  crown-  and  bridge- 
work,  and  is  recommended  to  the  inexperienced  because  the  melting 
of  a  part  of  the  crown  in  the  soldering  process  is  less  liable  to  occur  by 
its  use.  It  is  formed  by  fusing  a  thick  layer  of  pure  gold  over  a  piece  of 
platinum  about  gage  No.  30  and  passing  through  a  rolling  mill.  In 
soldering  the  seam  of  union  of  a  collar  made  of  this  style  of  plate,  the 
ends  of  the  metal  require  to  be  clamped  together  until  they  are  united 
by  the  solder,  as  otherwise  the  unequal  expansion  of  the  gold  and 
platinum  will  spring  them  apart  and  open  the  seam. 

Platinized  Gold. — An  alloy  of  pure  gold  with  from  i  to  3  per  cent, 
platinum  may  be  used  to  advantage  in  various  operations.  Gold 
so  alloyed  is  but  slightly  affected  in  color  and  is  very  flexible.  Plate 
of  this  alloy  can  be  used  exceedingly  thin  with  much  less  liability  of 
being  melted  than  pure  gold. 

Melting  and  Refining  of  Gold  Scraps. — The  conversion  of  gold 
scraps  into  plate  is  desirable  from  an  economic  standpoint. 

Passing  a  magnet  through  scraps  or  filings  will  remove  particles  of 
iron.  A  moderate  quantity  of  clean  scraps,  using  plenty  of  borax, 
can  be  melted  with  a  gas  blowpipe  and  allowed  to  cool  in  a  depression 
of  the  soldering-block.  For  a  large  quantity  use  a  small  crucible  well 
lined  with  borax,  fuse  in  a  gas  or  charcoal  furnace  and  pour  into  a 
warm  ingot-mold.  The  gold  should  be  allowed  to  cool  slowly  and 
should  never  be  removed  from  the  ingot-mold  and  immersed  in  water 
while  still  hot.  When  cool  the  ingot  should  be  boiled  in  acid,  cleaned, 
hammered  out,  annealed  and  rolled  in  a  mill  to  the  desired  gage. 

Filings  and  scraps  containing  particles  of  solder  should  be  melted 
and  refined  by  the  ''dry  process."  This  consists  in  placing  the  scraps 
in  a  crucible  lined  with  borax,  fusing  at  a  high  heat  for  a  considerable 
time  and  applying  potassium  nitrate  (saltpeter). 

Gold  Solders. — The  grade  and  character  of  solder  are  important 
in  crown-  and  bridge-work  operations.     The  solder  should  approach 


lO  CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 

the  fineness  of  the  plate  used,  exhibit  strength  and  elasticity  when 
in  plate  form  and  melt  and  flow  smoothly  under  the  properly  applied 
heat  of  the  blowpipe. 

The  production  of  solder  of  uniform  quahty  requires  a  knowledge 
and  skill  only  possessed  by  those  constantly  engaged  in  its  manufacture. 
For  this  reason,  although  some  operators  alloy  and  make  their  plate 
and  remelt  their  scraps,  very  few  prepare  their  solder.  When  pur- 
chased, the  name  i8-  or  20-carat  solder  does  not  imply  that  it  will 
assay  eighteen  or  twenty  carats  fine,  respectively,  but  that  the  figure 
gives  the  grade  of  plate  for  which  the  particular  solder  is  adapted. 

18-  and  20-carat  solders  are  used  for  crowns  and  bridges,  although 
some  dentists  consider  i8-carat  too  low  for  the  purpose.  22-carat 
solder  is  seldom  used  except  to  solder  the  joint  of  a  collar  or  on  the  ex- 
posed outside  surface  of  a  gold  crown.  14-carat  solder  is  used  only  in 
filling  the  cusps  of  seamless  crowns  in  single  crowning  operations  and 
in  some  repairing  operations. 

The  following  is  the  proportion  for  i8-carat  solder  generally  given 
in  text-books:^ 

Pure  gold 18      grs. 

Silver 2      grs. 

Copper 3      grs. 

Zinc iH  grs. 

The  burning  out  of  approximately  one-half  grain  of  zinc  gives  a  solder 
close  to  18  carats  fine.  Increase  the  copper  slightly  to  darken  the 
shade. 

Solder  may  be  made  by  alloying  the  same  grade  of  plate  upon  which 
the  solder  is  to  be  melted.  For  such  an  alloy  a  soft  quality  of  fine  brass 
wire  is  the  best.  Spelter  solder  is  also  used.  The  following  formula  is 
an  example: 

22-carat  plate 4  dwt. 

Fine  brass  wire 12  grs. 

Allowing  for  the  alloy  already  present  in  the  22-carat  plate,  the 
result  is  a  solder  fully  19  carats  fine.  A  smaller  proportion  of  alloy 
added  to  the  22-carat  plate  will  give  a  corresponding  result;  for  example, 
2  grs.  to  each  dwt.  will  produce  a  solder  about  20  carats  fine. 

Dr.  W.  H.  Dorrance  many  years  ago  supplied  the  following  practi- 
cal formula^  for  an  alloy  for  the  formation  of  different  grades  of  gold 

^  This  is  the  formula  generally  asked  for  at  State  Board  Examinations. 

2  This  formula  is  used  by  the  author,  and  is  convenient  and  reliable,  and 
with  it  any  grade  of  alloy  is  quickly  formed.  It  is  used  by  the  author  when  he 
makes  solder. 


PLATES  AND  SOLDERS  li 

solder,  the  proportion  of  the  alloy  used  determining  the  melting-point 
and  fineness  in  carat  of  the  solder: 

Pure  silver i  part 

Pure  zinc 2  parts 

Pure  copper 3  parts 

The  silver  and  copper  are  first  melted  together  in  a  crucible  lined 
with  borax  and  the  zinc  added  quickly  in  small  pieces,  stirring  the  mass 
meantime  with  a  clay  pipe-stem.  On  the  fumes  of  the  zinc  passing 
off,  it  is  immediately  poured  into  an  ingot-mold  or  a  large  wooden  pail 
filled  with  water.  4  grains  of  this  alloy  melted  with  20  grains  of  pure 
gold  will  result  in  a  solder  fully  20  carats  fine. 

Hard  Gold  Solder. — The  term  "hard  solder"  may  be  applied  to 
any  formula  or  carat  of  gold  when  used  as  a  solder  on  one  that  is  higher 
fusing.  Thus,  coin  gold  is  so  called  when  used  to  solder  pure  or  platin- 
ized gold  and  pure  gold  when  used  to  solder  platinum  or  platinized 
gold.  It  is  also  applied  to  the  successively  higher  grades  in  carat  of 
the  ordinary  gold  solders  in  which  a  gradually  smaller  percentage  of  zinc 
is  used. 

An  i8-carat  grade  of  "hard  solder"  is  conveniently  made  by  melting 
together  by  weight,  one- third  i8-carat  solder  to  two-thirds  i8-carat 
gold  plate;  20-carat  solder  and  plate  can  be  used  in  the  same  proportions 
to  form  a  higher  grade.  The  plate  is  first  melted  and  the  solder  added 
and,  when  cool,  rolled  out  to  the  desired  gage.^  To  form  a  lower  flowing 
solder  for  use  in  successive  stages  of  the  work,  melt  together  one  part 
by  weight,  gold  solder  to  one  part  of  gold  plate. 


Peeso  Formulas^ 

No.  I. — Coin  Gold  Solder  No.  2. — Hard  Flowing  Solder 

Coin  gold 8  dwt.  Melt  together  equal  parts  of  coin  gold 

i8-carat  solder 3  dwt.  8  grs.  and  Formula  No.  i  solder. 

Pure  copper 18  grs. 

No.  2  formula  makes  a  solder  21  carats  fine. 

These  two  alloys  as  solder  flow  freely  and  are  excellent  for  use  on  coin  gold. 

Fluxed  Solder  Filings. — Fluxed  gold  solder  filings  are  made  by 
filing  with  a  clean  flat  plate-file  a  thick  piece  of  solder  held  in  a  vise. 
The  filings  are  allowed  to  fall  into  a  box  or  on  a  sheet  of  paper  placed 
to  receive  them.  A  magnet  should  be  passed  through  the  filings  to 
remove  any  minute  particles  of  steel  from  the  file.     To  five  parts  of 

^  Formula  most  used  by  the  author. 
2  Dr.  F.  A.  Peeso. 


12  CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 

the  filings  so  prepared  is  added  and  well  mixed  with  them,  one  part  of 
Parr's  prepared  flux  or  finely  pulverized  vitrified  borax.  As  a  vehicle 
with  which  to  apply  the  filings  in  soldering,  add  enough  vaselin  to 
form  a  paste.  Solder  prepared  in  this  form  is  useful  for  strengthening 
crowns  and  also  in  fine  soldering  operations,  such  as  uniting  the  joints 
of  a  collar,  as  the  particles  of  solder  take  the  heat  separately  and  fuse 
much  more  quickly  than  when  the  solder  is  cut  in  pieces.  The  flow  of 
the  solder  is  also  more  easily  defined  and  limited. 

Platinum  Solder. — Platinum  solder  is  made  by  alloying  pure  gold 
with  15,  20,  or  25  per  cent,  of  platinum  and  fusing  with  a  compound 
blowpipe.  30  per  cent,  platinum  solder  withstands  the  very  highest  heat 
ever  used  in  the  fusing  of  porcelain.  Platinum  solder  is  used  to  unite 
the  platinum  sectional  frame- work  of  a  crown  for  porcelain- work  or  for 
a  casting  operation.  The  grade  of  solder  to  be  used  is  determined  by 
the  fusing  point  of  the  porcelain.  10  per  cent,  may  be  used  to  solder 
seams  of  platinum  caps  when  pure  gold  is  to  be  cast  over  it. 

Silver  Solder. — Silver  solder  is  frequently  used  by  the  student  and 
practitioner  in  the  construction  of  tubes  for  impressions  and  in  the 
construction  of  experimental  or  specimen  work  made  of  coin  silver, 
nickel  or  German  silver. 

A  reliable  formula  is: 

Coin  silver 90  parts 

Zinc 10  parts 

Low  fusing  silver  solder: 

Coin  silver 50  parts 

Spring  brass  wire 50  parts 

Flux. — The  object  of  flux  is  to  prevent  oxidation  of  the  metal  when 
heated  and  thus  permit  the  portion  which  is  fused  to  flow  freely  and 
unite  with  the  surfaces  of  the  higher  fusing  metal.  The  lower  grades 
of  alloys  require  more  flux  than  the  higher  grades,  as  is  evidenced  in  the 
soldering  of  platinum  with  pure  gold.  The  quantity  of  flux  applied  to 
the  work  for  soldering  should  be  limited  to  that  which  will  accomplish 
the  desired  object.  An  excess  of  flux  affects  the  control  of  solder, 
forms  pits  and  is  liable  to  reach  and  check  porcelain  by  fusing  upon  its 
surface. 

Borax  is  the  preferred  flux  for  soldering  dental  work.  For  small 
fine  soldering  and  deeply  invested  sections  it  should  be  ground  with 
water  on  a  slab  and  applied  with  a  fine  camel 's-hair  brush  before  heating 
the  metal  or  investment.  For  application  during  soldering  it  should  be 
first  vitrified  and  then  ground  to  a  fine  powder.     Vitrification  divests 


PLATES  AND  SOLDERS  13 

borax  of  its  water  of  crystallization  and  in  this  vitrified  form,  when 
powdered,  it  can  be  sprinkled  on  the  metallic  sectional  parts  of  the  work 
and  fused  without  disturbing  their  position  through  expansion,  which 
is  liable  to  occur  when  ordinary  pulverized  borax  is  used.  Preparations 
of  borax  should  be  kept  perfectly  clean,  as  the  invasion  of  foreign  matter 
will  cause  pits  in  the  solder.^ 

Dental  solder  of  a  higher  grade  than  that  ordinarily  used  in  the  arts 
requires  more  heat.  As  borax  melts  at  a  comparatively  low  heat,  its 
tendency  is  to  flow  off  the  prominent  points  of  the  metal  and  expose 
them.  Consequently,  as  the  addition  of  boric  acid  raises  the  fusing 
point  of  the  flux,  it  tends  to  increase  its  efficiency. 

A  formula^  for  solder  flux  is: 

C.  P.  borax  glass  (fused) 55  parts 

C.  P.  boric  acid  (not  fused) 35  parts 

C.  P.  silica 10  parts 


100  parts 


The  ingredients  are  fused  at  a  red  heat  in  fire-clay  crucible  and 
poured  into  cold  water,  then  instantly  removed,  dried,  pulverized  and 
passed  through  an  80-mesh  sieve.  This  £ux  is  applied  in  the  powdered 
form,  or  mixed  with  vaselin  to  form  a  paste,  or  dissolved  in  boiling 
water  and  the  saturated  solution  applied. 

Jewelers'  Liquid  Flux. — Jewelers'  liquid  flux  may  be  used  in  some 
parts  of  the  work  in  place  of  vitrified  borax  or  flux.  It  is  made  of  a 
saturated  solution,  equal  parts  borax  and  boric  acid  in  water.  It 
should  be  applied  to  the  parts  with  a  brush  before  heating  and  the 
heated  point  of  a  strip  of  solder  dipped  in  it  before  application. 

^  Dr.  Parr's  "Prepared  Flux,"  a  finely  pulverized  vitrified  flux,  can  be  used  in 
this  manner.  It  is  also  prepared  in  combination  with  wax  cement.  In  the  melting 
out  of  the  wax  when  the  case  is  invested  and  heated  for  soldering,  the  flux  is  carried 
into  the  interstices. 

2  Mr.  L.  J.  Weinstein's  formula. 


CHAPTER  III 

OTHER  MATERIALS 

FUSIBLE  ALLOYS — ^FORMULAS' — IMPRESSION  COMPOUND — DENTAL  LAC — 
MOLDINE — WAX  CEMENT— TO  SECURE  ADHESION  OP  WAX  TO  METAL 
OR  PORCELAIN — ^PORCELAIN  TEETH  OR  FACINGS — ESSENTIALS- 
FRACTURES,  CAUSES  OF — CHANGE  OF  SHADE  IN  BAKING  AND  SOLDER- 
ING   VENEERS — TO  CHANGE  SHAPE  OR  CONTOUR  OF  A  PORCELAIN 

TOOTH 

Fusible  Alloys. — Of  the  many  fusible  alloys  of  tin,  the  following — 
in  parts  by  weight — will  be  found  suitable  for  use  in  crown-  and 
bridge-work. 

Formulas 


Tin 

Lead 

Bismuth 

Melting-point 
Deg.  Fahr. 

5^ 

3 

8 

202 

3 

S 

8 

212 

I 
Tin 

2 

Lead 

2 

Bismuth 

236 

Cadmium 

Melting-point 
Deg.  Fahr. 

3 

4 

8 

2 

150 

22 

3 

5 

2 

180 

Fusible  metals  should  not^be  heated  beyond  their  melting  points, 
a  matter  which  is  not  as  a  rule  carefully  observed,  and,  after  fusing, 


Fig.  3. 

should  be  allowed  to  cool  moderately  before  pouring.  A  ladle,  such  as 
is  illustrated  in  Fig.  3,  with  legs  to  prevent  tipping  while  cooling,  is  a 
suitable  form. 

Impression  Compound. — Impression  compound  is  for  taking  im- 
pressions of  teeth  for  crown  and  inlay  work.  When  an  impression  of 
the  interproximal  or  other  small  space  between  the  teeth,  is  desired, 
it  is  best  obtained  by  first  placing  and  pressing  a  small  thin  piece  of  the 
material  used,  into  the  space  or  spaces  to  be  taken  before  pressing 
the  main  mass  in  the  impression  cup  to  position  in  the  mouth. 

1  Dr.  G.  W.  Melotte's  formula. 

2  Dr.  G.  Molyneaux's  formula. 

14 


OTHER  MATERIALS  15 

Impression  compound  is  softened  by  warm  water  or  dry  heat, 
preferably  the  former.  It  should  be  partly  or  entirely  hardened  by 
chilling  with  cold  water  before  removal. 

Dental  Lac. — This  is  a  preparation  resembling  sealing-wax.  It  is 
very  hard  and  tough  for  a  material  of  its  kind,  and  softens  and  hardens 
very  quickly  under  the  application  of  heat  and  cold.  It  is  softened  for 
use  by  holding  it  in  the  heat  above  an  alcohol  or  Bunsen  flame.  Den- 
tal Lac  will  maintain  its  form  in  the  swager  in  stamping  thin  soft  gold 
or  platinum  plate. 

Moldine. — This  is  a  preparation  compounded  of  potter's  clay  and 
glycerin.  More  glycerin  may  be  added  when  the  moldine  becomes 
hard.  It  is  of  putty-like  consistence  and  is  useful  in  forming  molds  of 
teeth  or  occlusal  surfaces  from  a  model  shaped  either  in  wax  or  plaster, 
which  is  to  be  cast  in  fusible  metal. 

Wax  Cement. — Wax  cement  is  used  in  two  forms,  adhesive  and 
hard  wax.  Adhesive  wax  when  moderately  heated  is  quite  flexible, 
adheres  readily  to  metal  and  porcelain,  and  may  be  manipulated  with  the 
fingers  without  sticking  to  them.  When  chilled  with  cold  water,  it 
becomes  quite  hard.  It  is  to  be  used  during  the  adaptation  of  different 
parts  of  the  work  in  and  out  of  the  mouth. 

Adhesive  wax  of  a  suitable  quality  can  be  made  of  pure  yellow 
beeswax  4  parts,  resin  i  part,  and  gum  dammar  i  part,  by  weight. 

Hard  wax  requires  more  heat  to  soften  it  than  the  adhesive  kinds. 
When  sufficiently  heated  it  is  very  soft  and  adhesive,  but  exceedingly 
brittle  when  cooled.  It  is  best  used  as  a  support  to  adhesive  wax;  the 
adhesive  wax  having  been  first  applied  in  the  preliminary  adaptation 
of  the  work,  as  much  as  possible  of  it  is  removed  without  disturbing 
the  position  of  the  parts  and  replaced  with  the  hard  wax  for  the  final 
adjustment. 

Hard  wax  is  made  of  yellow  beeswax  i  part  and  resin  3  parts,  by 
weight. 

Wax  cement  in  the  form  of  sticks  is  the  most  convenient  for  use. 

To  Secure  Adhesion  of  Wax  to  Metal  or  Porcelain. — Heated  or 
melted  wax  when  applied  to  a  cold  or  wet  surface  does  not  adhere 
properly  and  is  liable  to  loosen  and  cause  displacement  of  sections  of 
the  fitted  work.  To  prevent  this,  dry  the  metal  or  porcelain  perfectly 
and  heat  it  uniformly  to  a  point  that  will  fuse  the  wax  when  touched  to  its 
surface.  Veneer  the  surface  of  the  metal  or  porcelain  with  the  wax 
and  allow  it  to  partly  or  entirely  cool.  Wax  then  applied  will 
adhere  firmly  to  the  wax  veneer. 

Porcelain  Teeth  or  Facings. — The  artificial  teeth  chiefly  used  in 
crown-  and  bridge- work  operations  are  termed  porcelain  facings. 


1 6  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Essentials  of  Porcelain  Teeth. — The  qualities  requisite  in  porcelain 
tooth  body  for  use  in  crown-  and  bridge- work  are  density,  strength  and 
the  power  to  withstand  unaltered  in  form  or  shade  any  degree  of  heat 
to  which  it  may  necessarily  be  subjected.  In  these  respects  the 
porcelain  teeth  of  our  best  American  manufacturers  seem  to  excel. 
They  afford  at  the  same  time  those  other  essentials,  artistic  imitation 
of  the  natural  teeth  in  form  and  shade,  and  practical  location  of  the 
pins. 

Fractures  in  Porcelain  Teeth,  Causes  of. — Porcelain  facings  are 
sometimes  fractured  in  soldering  by  the  contraction  of  the  backing 
when  adapted  over  the  edges  of  the  porcelain  in  an  acute  instead  of  an 
obtuse  angle,  or  by  the  melting  of  solder  on  some  part  of  the  porcelain 
which  is  unprotected  by  a  backing  of  metal.  The  cooling  solder  or 
borax  contracting  on  the  porcelain,  or  a  very  thin  edge  of  the  metal 
covering  it,  will  usually  cause  a  fracture.  The  porcelain  tooth  has 
yet  to  be  made  that  will  endure  such  extreme  treatment  without 
breaking. 

Porcelain  facings  set  up  for  soldering  with  their  sides  touching  aie 
very  liable  to  fracture  by  expansion.  An  imperceptible  space  of  at 
least  3^^00  0  inch  should  be  left  between  them.  Fractures  are  also 
caused  by  too  rapid  heating  and,  quite  frequently,  because  the  op- 
erator removes  the  work  from  the  investment  before  it  has  become 
perfectly  cool. 

Changes  of  Shade  in  Baking  and  Soldering. — The  shade  of  porce- 
lain teeth  is  very  slightly  affected,  if  at  all,  by  an  ordinary  soldering 
operation.     Subjecting   them   to    extremely  high  heat  in  a 
furnace  tends  to  lighten  the  porcelain  by  burning  out  some 
of  the  metallic  oxids  or  other  compounds. 

To  closely  determine  the  shade  developed  by  soldering, 
which  may  at  times  be  necessary  in  the  restoration  of  one 
of  the  six  front  teeth,  back  the  facing  with  %ooo  platinum, 
invest,  heat  slowly  and  reinforce  the  platinum  substantially 
with  pure  gold.  The  shade  thus  developed  will  be  very  little 
affected  subsequently,  if  at  all,  by  the  comparatively  low  heat 
required  to  fuse  ordinary  i8-  or  20-carat  solder, 
p  Repeated  soldering  operations  and  the  use  of  alloys  composed 

largely  of  the  base  metals  tend  to  darken  the  shade  of  porcelain. 
Veneers. — A  veneer  consists  of  a  thin  piece  of  porcelain  represent- 
ing the  labial  aspect  of  a  natural  tooth. 

To  form  a  veneer  select  a  porcelain  facing  of  the  required  shade  and 
size.  On  the  end  of  a  piece  of  wood  about  the  size  of  the  facing,  melt 
and  attach  a  mass  of  shellac,  heat  the  porcelain  facing  and  imbed  the 


OTHER  MATERIALS  17 

labial  surface  in  the  shellac,  as  shown  in  Fig.  4.  Clip  off  the  pins  of 
the  facing  and  with  a  carborundum  wheel  on  the  lathe  grind  down  the 
porcelain  uniformly  to  the  required  thickness.  Heat  the  porcelain, 
release  the  veneer  and  remove  all  particles  of  shellac  before  the  ap- 
plication of  the  veneer  to  the  case. 

To  Change  Shape  or  Contour  of  a  Porcelain  Tooth. — Trim  the 
surface  of  the  porcelain  to  the  desired  form- and  polish,  first  with  coarse 
carborundum  disks,  then  with  finer  grades,  finishing  with  cuttlefish 
and  oxid  of  tin  (putty).  If  the  restoration  of  the  original  glaze  is 
desired  after  polishing,  place  the  tooth  on  pulverized  silex  on  a  fire- 
clay slab  and  heat  in  the  electric  furnace  up  to  over  2400°  for  American 
and  about  2000°  for  English  rnanufacture.  The  porcelain  will  then 
appear  with  its  original  glaze. 


CHAPTER  IV 
APPLIANCES  AND  METHODS 


lAIPRESSION  TRAYS — ARTICULATORS — IMPRESSIONS — SECTIONAL  IMPRES- 
SIONS— ROACH  SECTIONAL  IMPRESSION  TRAY — MODELS — A  HARD 
SURFACE — TO  HARDEN  PLASTER  MODELS — ARTIFICIAL  STONE — 
ARTICULATING  IMPRESSION  OR  "bITE"  AND  MODEL^ — COMBINA- 
TION   PLASTER    AND    METAL    MODEL — COPPER    AMALGAM    MODELS 

Impression  Trays. — In  crown-  or  bridge-work  operations,  as  an 
impression  of  only  a  portion  of  the  teeth  is  generally  required,  partial 
impression  trays  are  mostly  used.     Trays  suitable  for  the  right  and 


left  sides  and  front  of  the  mouth  are  illustrated  in  Figs.  5  and  6.  They 
are  of  forms  that  favor  the  replacement  of  a  plaster  impression  in  the 
tray  should  it  break  or  be  disturbed  in  removal  from  the  mouth.  Fig. 
7  is  an  adjustable  partial  impression  tray.     This  device  conveniently 


18 


APPLIANCES  AND  METHODS 


19 


takes  the  place  of  three  trays.  The  tray  proper  rotates  on  a  pivot, 
B,  and  is  thus  perfectly  adapted  for  use  in  the  front  or  on  either  side  of 
the  mouth,  and  is  firmly  held  in  position  by  the  sliding  guard  A. 


Fig.  6. 


Pig.  7. 


Articulators. — The  ordinary  and  anatomical  forms  of  articulators 
are  used  in  bridge- work,  especially  the  latter  for  large  operations  em- 
bracing both  sides  of  the  mouth.  For  small  bridges  or  single  crowns 
the  partial  or  an  anatomical  articulator  with  a  graduating  support, 


20 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


such  as  is  illustrated  in  Fig.  8,  is  much  used.     Fig.  9  shows  an  anatom- 
ical articulator.     (Kerr's). 

Impressions. — For  the  taking  of  impressions  for  bridge-work  and 
for  most  operations  in  crown- work,  plaster  is  most  suitable.  To  sim- 
plify the  separation  of  the  impression  from  the  model,  a  particle  of 
carmine  or  other  coloring  material  may  be  combined  with  the  plaster 
in  the  mixing.  Potassium  sulfate,  if  added,  wUl  quicken  the  setting. 
The  best  method  for  the  purpose  is  to  dissolve  a  small  teaspoonful 


Fig.  8. 


Pig.  9. 

of  the  potassium  sulfate  in  a  pint  bottle  of  water  and  thus  always  have 
it  ready  for  use  in  the  proper  proportions.  The  improved  impression 
compound  is  serviceable  for  impressions  and  "bites"  for  crowns  and 
small  bridges.  It  is  softened  with  a  moderate  heat  and  quickly  becomes 
hard  again  on  the  apphcation  of  cold.  It  does  not  fracture  as  easily 
as  plaster.  This  compound  is  much  used  for  taking  impressions  for 
inlay  work  by  the  indirect  method. 

Sectional  Impressions. — When  the  exact  form  of  the  contour  of  a 
tooth  is  required  or  when  teeth  tip  toward  each  other  in  such  manner 
that  in  the  taking  of  an  impression  the  mass  of  plaster  that  sets  around 


APPLIANCES  AND  METHODS 


or  between  them  will  not  pull  out,  the  best  plan  is  to  take  the  impres- 
sion one  half  at  a  time  with  a  split  tray  which  is  jointed  in  the  middle 
by  a  hinge.  A  brass  hinge  may  be  used  to  form  a  split  impression  tray, 
as  shown  in  Fig.  lo.     An  impression  may  also  be  taken  in  sections  (Fig. 


Pig.  10. 


Fig.  II. 


ii).  Take  the  lingual  and  part  of  the  incisal  or  occlusal  surfaces 
first,  remove  that  section,  trim,  varnish  and  oil;  replace  in  position  in 
the  mouth  and  apply  plaster  to  form  the  remaining  section.  Separate 
the  sections  for  removal  from  the  mouth,  replace  and  run  the  model. 


Fig.  12. 

An  impression  of  this  character  may  also  be  obtained  by  taking  the 
lingual  side  first  with  impression  compound  and  then  the  labial  with 
plaster,  so  that  it  will  include  the  entire  occlusal  and  incisal  parts. 
This  method  will  sometimes  simplify  the  taking  of  a 
difficult  impression  for  bridge-work. 

A  method  for  use  in  contracted  spaces  for  re- 
moval of  abutment  crowns  in  the  impression,  is  to 
fit  a  piece  of  softened  impression  compound  accurately 
in  position  between  the  overhanging  teeth,  so  shaped 
that  it  will  pull  out  of  the  plaster  impression  on  re- 
moval, as  shown  in  Fig.  12.  The  piece  of  compound 
is  removed  from  its  position  in  the  mouth  and  replaced  in  the 
impression  to  complete  the  mold. 

When  the  line  of  the  interproximal  space  between  certain  teeth  is 
required,  it  is  best  obtained  by  inserting  between  the  teeth,  before 
taking  the  impression,  a  piece  of  separating  file,  as  shown  in  Fig.  13, 


Fig.  13. 


22 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


or  a  strip  of  copper,  single  or  doubled  so  that  it  fits  the  space  closely, 
with  the  ends  protruding,  and  removing  it  in  the  plaster. 

In  this  class  of  work  the  surfaces  of  all  plaster  impressions  that  are 
to  be  run  with  plaster  require  to  be  thoroughly  varnished  and  oiled. 


Fig.  14. 

Roach  Sectional  Impression  Tray. — Fig.  14  illustrates  the  Roach 
Sectional  Impression  Tray.  A  is  intended  for  taking  impressions  of 
teeth  standing  alone.  It  is  closed  on  both  ends  and  has  centrally 
located  flanges  to  aid  in  splitting  the  plaster  in  two  sections  to  permit 
its  removal.  B  is  for  taking  an  impression  of  a  space  with  teeth  on  one 
end  and  none  on  the  other. 


Fig.  15. 

Fig.  15  shows  the  handle  in  position  on  the  closed  tray  ready  to  use. 
The  tray  is  filled  with  plaster  and  pressed  to  position  in  the  mouth. 
When  the  plaster  is  set  the  handle  is  withdrawn,  the  impression  parted 
in  the  center,  which  is  aided  by  the  flanges,  and  removed.  The  two  sec- 
tions are  then  joined  and  the  handle  readjusted  to  lock  them  together. 


Fig.  16. 

Fig.  16  shows  a  separated  and  closed  impression  of  a  tooth,  in  a 
Roach  Tray,  also  the  plaster  formed  model  of  the  tooth. 


APPLIANCES  AND  METHODS  23 

Models 

Models. — Models  on  which  bridge-work  is  to  be  constructed  but 
not  soldered,  are  made  of  plaster.  To  permit  removal  of  the  caps  or 
crowns  from  the  model^dunng^the  construction  of  the  bridge,  the  inside  of 
the  caps  should  be  veneered  with  paraffin  to  fill  in  recesses;  also  the 
surfaces  of  posts  or  tubes  to  permit  them  to  be  easily  withdrawn  from 
the  plaster.  The  exposed  outer  cervical  surfaces  of  the  collars  in  the 
impression  should  be  coated  with  paraffin  to  prevent  the  edges  of  the 
collars  scraping  the  plaster  of  the  model  in  reinserting  and  pushing  the 
scrapings  into  the  grooves  into 
which  the  edges  of  the  collars  fit 
(Fig.  17).  The  mere  cervical  edge 
of  the  collar  should  be  left  free  of 
the   paraffin  to  permit  it  to  sit 

closely  in  the  model.  Fig.   17. — W.  Paraffin  or  wax. 

Models  on  which  bridge-work 
is  to  be  formed  and  soldered  should  be  made  of  a  material  as 
non-shrinkable  when  heated  as  is  practicable.  Plaster  and  finely 
ground  calcined  marble-dust  or  pulverized  silex,  mixed  in  the 
proportion  of  3  parts  marble-dust  or  silex  to  i  part  plaster  for  large 
models,  and  3  parts  marble-dust  or  silex  to  2  parts  of  plaster, 
for  small  models,  are  suitable  proportions.  Slips  of  orange- wood, 
iron  pins  or  small  nails  may  be  placed  in  the  impressions  of  such  teeth 
as  are  liable  to  be  broken  in  the  removal  of  the  impression  from  the 
model.  Should  fracture  occur,  a  thin  mixture  of  oxyphosphate  cement 
should  be  used  to  repair  the  parts,  as  this,  when  thoroughly  set,  makes 
them  even  stronger. 

A  Hard  Surface.' — A  model  of  investment  material  for  bridge-work 
can  be  given  a  hard  pure  plaster  surface  as  follows :  First  place  with  a 
camel's-hair  brush  in  the  impression  of  the  teeth  and  also  the  surface 
of  the  alveolar  ridge  a  film  of  a  thin  mixture  of  pure  plaster,  and  when  it 
has  partly  set,  fill  the  remainder  of  the  impression  with  a  mixture  of 
plaster  and  marble-dust  or  silex.  This  to  be  effective  must  be  skil- 
fully done. 

To  Harden  Plaster  Models. — The  surface  of  models  of  plaster  or 
investing  material  can  be  hardened  by  first  drying  the  plaster  by 
placing  it  in  the  rays  of  the  sun  in  the  summer  or  over  a  radiator  in  the 
winter,  thus  drying  it  slowly.  It  should  never  be  highly  heated  as 
that  makes  it  chalky.  Several  coats  of  very  thin  sandarac  varnish, 
diluted  to  about  two-thirds  the  usual  consistence,  are  then  applied 
at  intervals  to  the  surface.     Immersion  of  plaster  models  in  melted 


24  CROWN;  BRIDGE-,  AND  PORCELAIN-WORK 

stearin   is   also  recommended,  but  for  a   working  model  varnish   is 
preferable. 

Artificial  Stone.- — Weinstein's  artificial  stone,  a  calcium  silicate 
compound,  is  used  to  some  extent  to  form  models.  It  is  hard  and 
durable,  and  models  made  of  it  when  worked  on  are  not  distorted  by 
friability. 

Wax  or  compound  impressions  for  artificial  stone  models  require 
no  preparation,  but  plaster  should  be  well  varnished,  first  with  shellac, 
and  when  thoroughly  dry  with  sandarac.  The  impression  is  then 
soaked  in  water  about  five  minutes,  removed,  and  the  water  shaken 
and  blown  out,  leaving  the  surface  moist.  The  purpose  is  to  avoid 
any  absorption  by  the  plaster  of  moisture  from  the  slow-setting 
artificial  stone,  which  would  affect  the  setting. 

In  the  mixing  of  Weinstein's  artificial  stone  the  powder  must  be 
accurately  proportioned  to  the  water,  one-half  fluidounce  of  water  to 
every  four  and  one-half  to  four  and  five-eighths  oz.  avoirdupois,  which 
is  equivalent  to  80  to  82  dwt.  (Troy)  of  the  powder.  This  makes  a 
thick  mix  that  requires  to  be  thoroughly  spatulated.  As  it  cannot  be 
poured  it  is  inserted  in  deep  places  with  a  small  stiff  brush  followed 
with  pieces  in  the  form  of  cones — ^proportioned  to  the  size  of  the  space 
■ — which  can  be  pressed  on  with  the  rubber  eraser  end  of  a  pencil.  The 
remainder  of  the  impression  is  then  filled  with  larger  pieces  until  it  is 
full,  when  a  surplus  is  added.  The  impression  and  model  are  then 
reversed  against  the  surface  of  a  piece  of  glass  and  pressure  exerted 
sufficient  to  uniformly  condense  the  entire  mass.  While  the  model  is 
pressed  on  it  is  leveled  around  the  sides  of  the  impression  with  the 
spatula. 

Healey^s  artificial  stone  must  be  mixed  with  water  that  has  been 
just  brought  to  a  boil,  then  treated  and  inserted  in  the  impression  or 
mold  in  the  same  manner  as  the  Weinstein.  It  forms  a  pure  white 
model. 

This  artificial  stone  sets  as  hard  as  plaster  in  from  five  to  six  horns. 
When  it  is  that  hard,  the  model  should  be  trimmed  to  the  desired  form 
and  removed  from  the  impression,  unless  it  is  a  model  considered 
preferable  to  leave  in  the  impression  a  few  hours  longer  until  it  becomes 
harder.  It  acquires  its  maximum  hardness  of  form  in  one  to  two  days 
and  maintains  it  indefinitely. 

Articulating  Impression  or  "Bite"  and  Model. — This  impression  is 
either  taken  separately  or  at  the  same  time  with  the  impression  for  the 
model;  the  last  is  the  most  accurate  method.  When  taken  separately 
it  should  be  done  with  all  the  crowns  or  caps  in  position  in  the  mouth 
previous  to  the  impression  for  the  model.     Wax  is  more  generally  used 


APPLIANCES  AND  METHODS  25 

for  a  separate  "liite"  than  impression  compound.  Softened  wax 
barely  sufficient  to  cover  the  parts  is  pressed  over  the  teeth  and 
crowns  to  their  form,  and  the  antagonizing  teeth  then  occluded.  The 
finger  or  cheek  is  pressed  against  the  outside  of  the  wax  and  the  patient 
is  requested  to  press  the  tongue  against  it  on  the  inside.  The  mouth  is 
then  opened,  the  wax  chilled  with  cold  water  and  removed.  To  secure 
accuracy  it  is  often  necessary  to  trim  the  impression  of  overhanging 
or  superfluous  parts  and  reinsert  it  a  second  time.  Pieces  of  tin  foil 
placed  over  the  teeth  which  antagonize  before  inserting  the  wax  will 
prevent  their  biting  through  the  impression. 

Another  method  is  to  close  the  mouth  so  that  the  teeth  and  crowns 
do  riot  quite  occlude,  and  mount  the  model  and  impression  on  a  hinge 
articulator  that  will  permit  teeth  and  crowns  to  occlude  after  the  mod- 
els are  mounted  and  the  impression  material  is  removed. 

When  the  model  with  the  crowns  has  been  made,  the  articulating 
impression,  if  taken  separately,  is  placed  in  position  on  it,  an  articulat- 
ing model  run  and  both  models  mounted  on  an  articulator. 

When  impressions  for  both  model  and  "bite"  are  to  be  taken 
together,  plaster  mixed  moderately  thick  with  the  aid  of  a  spoon  or 
rolled  in  a  mass  with  the  fingers  is  used.  The  fingers  should  be  pre- 
viously immersed  in  water  to  prevent  adhesion  of  the  plaster  to  them. 
The  stiff  plaster  is  placed  around  in  the  mouth,  on  the  crowns,  caps 
and  parts  to  be  included  in  the  bridge  and  the  antagonizmg  teeth  then 
occluded  tightly  and  so  held  until  the  plaster  sets.  The  mouth  is 
then  opened  and  the  plaster  carefully  removed.  If  it  breaks  in  re- 
moval, which  is  usually  the  case,  all  the  pieces  should  be  preserved, 
accurately  fitted  together  and  secured  in  position  with  small  pieces  of 
melted  wax.  The  crowns  or  caps  are  generally  removed  in  the  im- 
pression; but  if  not,  they  should  be  transferred  from  the  mouth  to  the 
plaster.  The  plaster  is  then  varnished  and  oiled.  On  the  side,  of  the 
impression  containing  the  crowns,  if  they  are  to  be  removed  from  the 
model  in  the  construction  of  the  bridge,  a  plaster  model  is  run,  or,  if 
not  to  be  removed,  plaster  and  marble-dust  or  silex  in  the  proportions 
already  mentioned  is  used.  When  the  plaster  has  set,  the  model  is 
mounted  on  an  articulator  and  an  articulating  model  of  pure  plaster 
run  and  the  opposite  section  adjusted  for  the  articulator.  The  im- 
pression plaster  is  next  removed.  (For  further  details  see  Part  VI, 
Chapter  I.) 

Combination  Plaster  and  Metal  Model. — A  method  of  forming  a 
model  in  which  the  parts  representing  the  teeth  are  of  amalgam  is  as 
follows:  Take  an  impression  in  plaster  or  impression  compound.  Mix 
amalgam  and  pack  it  into  each  of  the  molds  of  the  teeth  or  roots  and 


26  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

run  plaster  into  the  remainder  of  the  impression.  The  advantage  of  a 
model  of  this  kind  when  gold  attachments  or  clasps  are  to  be  shaped  to 
teeth  is  obvious.  Amalgam  can  also  be  used  in  abutment  caps,  there- 
by permitting  them  to  be  removed  and  accurately  replaced  on  the 
model  with  a  certainty  not  found  in  the  use  of  plaster.  Both  the 
inside  and  the  outside  of  the  gold  caps  should  be  veneered  with  paraffin. 
The  paraffin  and  all  the  exposed  portions  of  the  metal  are  then  given 
one  or  two  coats  of  collodion.  When  the  collodion  is  dry,  the  entire 
impression  is  oiled  in  the  usual  manner.  Amalgam  from  which  all 
excess  of  mercury  has  been  pressed  is  packed  into  the  caps,  using 
moderate  pressure.  A  short  cone  of  the  amalgam  is  left  extending 
from  each  cap,  which  may  be  slightly  scratched  or  indented.  The 
plaster  is  next  run  into  the  impression  and  the  case  is  put  aside  until 
the  next  day  before  separation.  In  the  case  of  a  cap  with  a  post  or 
tube,  if  the  amalgam  is  only  placed  around  the  point  or  sides  of  the 
post  or  tube  it  will  aid  proportionately  in  defining  the  position  of  the 
cap  in  replacing  it  when  it  has  been  removed  from  the  model.  The 
caps  and  crowns  when  removed  from  the  model  should  be  cleaned  by 
boiling  in  water  and  sodium  carbonate  and  next  in  nitric  acid  to  remove 
any  trace  of  the  amalgam  that  might  have  adhered. 

Oxyphosphate  of  zinc  or  copper  cement  may  be  used  quite  effectively 
instead  of  amalgam  as  above  described  and  the  precautions  required  to 
avoid  amalgamation  of  the  mercury  of  the  amalgam  with  the  gold  of 
the  caps  avoided. 

Another  method  of  forming  a  combined  metal  and  plaster  model 
much  practiced,  especially  for  inlay  work,  is  to  first  make  amalgam  or 
fusible  dies  with  tapering  shanks  of  the  teeth  or  roots  operated  on, 
then  take  a  wax  impressiofi  and  "bite."  Run  plaster  in  the  "bite"  sec- 
tion and  when  set,  fit  the  dies  into  the  respective  impressions  in  the  wax 
and  run  the  remainder  of  the  impression  with  plaster,  then  mount  on 
an  articulator.  To  make  a  die  easy  to  remove  from  the  model,  veneer 
the  surface  of  the  shank  with  paraffin.  A  hole  made  in  the  base  of 
the  model  in  a  line  with  the  end  of  the  shank  of  a  die  can  be  used  to 
introduce  an  instrument  to  push  the  die  from  position  when  it  is 
desirable  to  remove  it  from  the  model  and  use  it  separately. 

Copper- Amalgam  Models. — Models  of  this  form  are  at  present 
much  used  in  the  construction  of  bridge-work.  The  impression  re- 
quires to  be  taken  in  plaster  in  a  sectional  impression  cup  so  as  to 
secure  the  exact  contour  of  the  teeth,  or  it  may  be  taken  in  the  form  of 
an  impression  and  "bite"  if  the  fractured  portions  of  the  impression 
are  skilfully  replaced  in  position. 


APPLIANCES  AND  METHODS  27 

Copper  amalgam  is  manipulated  by  gently  heating  the  tablets  in  a 
spoon  to  soften  them.  The  mass  is  next  transferred  to  the  surface  of 
a  clean  piece  of  thick  paper,  and  spatulated  with  a  stiff  steel  spatula 
until  smooth  and  plastic.  It  should  be  carefully  and  thoroughly 
packed  into  the  impression  and  then  placed  aside  to  set  until  the  next 
day.  The  models  are  then  mounted  with  plaster  on  an  articulator  and 
the  plaster  impression  removed.     It  gives  a  hard,  smooth  model. 

Copper  amalgam  can  be  re-softened  and  used  several  times.  For 
this  reason  it  is  much  less  expensive  than  the  silver-tin  amalgams. 


CHAPTER  V 
MOLDS  AND  DIES 

TUBES,  CAPS  AND  TRAYS — HOW  TO  MAKE  A  TUBE  QUICKLY — ^IMPRESSION 
FOR  FUSIBLE  METAL  DIE — MOLDINE — CASTING  THE  DIE — COUNTER- 
DIES COMBINATION    LEAD    AND    FUSIBLE-METAL    COUNTER-DIES 

AMALGAM  DIES — AMALGAM — THE  SWAGER^ — SWAGING 

Molds  or  impressions  of  single  teeth;  also  cavities  in  teeth,  are 
taken  in  metallic  tubes,  caps  or  small  trays  with  some  one  of  the  im- 
pression materials  used  for  the  purpose.  Stamped  seamless  caps  or 
tubes  can  be  used;  also  trays  formed  from  seamless  caps  by  trimming 
and  shaping  the  caps.  Copper  plate  not  heavier  than  gage  No.  32  is 
generally  the  most  suitable  for  making  tubes,  but  a  much  thinner 
plate  may  be  used  when  it  is  required  to  be  passed  between  the  teeth. 

Tubes,  Caps  and  Trays 
How  to  make  a  Tube  Quickly. — Take  a  thin  strip  of  copper  plate 
about  gage  No.  35,  anneal  and  bend  it  around  the  tooth  in  the  mouth 
or  its  form  on  the  plaster  model.  Both  ends  of  the  copper 
at  the  part  lapped  are  next  cut,  as  shown  at  A,  Fig.  18, 
and  turned  over  tight  and  close  in  the  manner  seen  at  B. 
This  fastens  the  ends  which,  when  trimmed  off  at  C,  form  a 
tube.  When  one  end  requires  extensive  trimming  to  fit 
the  curve  of  a  gum  margin,  the  seam  should  be  soldered 
with  a  small  piece  of  either  silver  or  14-carat  gold  solder. 
To  take  the  mold  of  the  end  of  the  root  or  the  whole 
or  part  of  the  natural  crown,  the  end  of  the  tube  should  be 
trimmed  to  the  curve  of  the  gum  and  inserted  under  the 
gum  margin.     Caps  are  fitted  in  a   similar  manner. 


Fig.  19. 

Trays  are  used  to  make  the  mold  or  impression  of  occlusal  surfaces 
or  cavities  formed  in  teeth  for  inlays.  A  tube  or  cap  when  trimmed  so 
that  it  encompasses  only  a  portion  of  the  crown,  as  shown  in  Fig.  19 

28 


MOLDS  AND  DIES 


29 


Fig.  20. 


at  A,  to  take  an  occlusal  surface,  or  at  B  for  both  occlusal  and  approxi- 
mal  surfaces,  is  practically  a  small  tray. 

The  formation  of  trays  and  their  use  in  inlay  work  together  with 
tubes  and  caps  is  described  in  Part  III,  Chapter  XVIII. 

Impression  for  Fusible-Metal  Die. — Fill  the  fitted  tube  or  cap  with 
plaster  mixed  as  for  an  impression,  apply  on  root  or  tooth 
and  press  to  position.  In  using  a  tube  press  the  index 
finger  on  the  open  end  of  the  tube  and  force  the  surplus 
plaster  downward  in  the  tube.  Hold  in  position  until 
the  plaster  is  set. 

Moldine. — The  application  is  similar  in  principle  to 
plaster.  The  surface  of  the  moldine  should  be  dusted 
with  pulverized  soapstone  to  avoid  adhesion. 

Casting  the  Die. — Closely  encircle  the  tube  or  cap 
with  a  strip  of  paper.  Place  a  rubber  band  around  the 
paper  to  secure  it,  as  shown  in  Fig.  20.  Hold  the  paper 
and  tube  with  a  clamp;  melt  and  pour  the  fusible 
metal,  moderately  cool,  and  immerse  tube  and  metal  in 
water.  This  gives  a  die  with  a  long  narrow  shank,  but  which  may 
require  trimming  at  the  neck.  Plaster  molds  are  generally  more 
accurate  then  moldine  and  give  better  results  in  casting. 

Impression-compound  or  gutta-percha  used  as  a  mold  for  fusible 
metal  is  not  reliable.  Such  a  mold  when  used  should  be  cooled  in 
ice  water  and  dried  before  pouring  the  fusible  metal,  which  should  be 
one  that  will  melt  at  not  higher  than  150°  F, 

Counter-Dies. — A  counter-die  to  a  small  die  of  fusible  metal  is 
made  by  indenting  a  block  of  lead  with  a  punch  about  the  size  of  the 

die  and  then  driving  the  cast  or  die  into  it. 
Its  use  in  crown-work  is  described  in 
Part  III,  Chapter  VII. 

A  counter-die  of  fusible  metal  to  a 
fusible  metal  die  may  be  made  either  by 
chilling  the  male  die  and  oiling  or  vaselining 
its  surface  or  coating  it  with  moistened 
whiting  with  a  brush,  and  after  drying 
pouring  the  additional  metal  as  it  cools. 
Combination  Lead  and  Fusible-Metal  Counter-Die. — This  is  made 
as  follows:  Cut  two  disks  of  thick  sheet  pattern  tin,  such  as  is  used 
to  form  patterns  for  gold  plates,  or  of  rolled  sheet  lead,  which  is  pre- 
ferable, in  sizes  that  will  fully  cover  that  section  of  the  surface  of  the 
male  die  where  the  metal  is  to  be  swaged.  Slit  the  disks  from  sides  to 
center,  as  seen  in  Fig.  21,  which  shows  disks  and  die.     Place  one  disk. 


Fig.  21. 


30 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


on  the  die  and  lap  it  down  on  the  sides.  Press  or  hammer  the  occlud- 
ing surface  against  a  tightly  rolled  ball  of  cotton;  next  shghtly  vaselin 
the  surface  of  the  tin  and  fit  over  it  in  like  manner  the  other  disk.  Imbed 
the  die  in  moldine  up  to  and  slightly  over  the  edge  of  the  tin,  place 
around  it  a  metal  ring  and  pour  fusible  metal.  When  cold,  remov  the 
disk  next  to  the  male  die.  This  leaves  a  slight  space  for  the  metal 
plate  which  is  to  be  swaged. 

Amalgam  Dies.^ — Amalgam  is  given  preference  to  fusible  metal  and 
all  other  materials  to  form  small  dies  in  crowning  and  inlay  opera- 
tions, as  it  is  certain  to  afford  sufficient  strength  with  great  accuracy 
of  details.  Its  use  is  principally  confined  to  the  formation  of  dies  in 
impressions  taken  with  compound.  The  compound  is  warmed,  the 
impression  taken  in  a  tube,  cap  or  tray,  and  cooled  before  removal.  The 
amalgam  is  then  packed  in  and  compressed.  If  the  shank  requires 
lengthening,  wind  round  the  tube  or  cap  a  very  thin  strip  of  copper 
secured  with  a  string. 

If  the  impression  is  taken  in  a  tray,  detach  or  cut  off  the  handle,  mix 
plaster  to  a  thick  creamy  consistence,  place  a  small  quantity  on  a  piece 
of  paper  and  set  the  back  of  the  tray  on  its  surface,  gently  pressing  the 
tray  down  into  the  plaster  so  as  to  form  a  cup-shaped  cavity  around  the 
impression.  This  furnishes  the  means  of  packing  and  then  compress- 
ing the  amalgam  into  the  impression  (Fig.  22). 


IMP.  ^-npUAilum/ 

p.  Piaini' 

Pig.  22. 


Fig.  23. 


Amalgam. — ^The  silver-tin  amalgams^  are  mostly  used  instead  of 
copper  amalgam  for  making  small  dies  in  molds  of  impression  compound. 

The  required  quantity  of  the  silver-tin  alloy  is  placed  in  a  mortar 
with  a  surplus  of  mercury  and  ground  until  the  mercury  incorporated. 
It  is  then  rolled  in  a  ball,  inclosed  in  a  piece  of  rubber  dam,  as  shown 
in  Fig.  23,  and  rubbed  quickly  in  the  palm  of  the  hand.     The  amalgam 

^  The  Black  Formula  alloys  are  of  this  character. 


MOLDS  AND  DIES 


31 


mixture  by  this  method  will  become  very  plastic  and  capable  of 
adaptation  to  the  finished  margins  of  the  mold. 

A  small  portion  of  the  amalgam  should  be  first  inserted  and  burn- 
ished with  a  small  ball  burnisher  without  pressure  to  all  parts  of  the 
impression,  then  more  amalgam  added  until  the  surface  is  entirely 
covered  and  the  impression  is  filled  gradually  but  solidly. 

Amalgam  dies  should  be  allowed  to  stand  over  night.  The  impres- 
sion and  die  are  separated  by  warming  the  compound  slightly  or  by 
immersing  the  impression  and  die  in  warm,  but  not  boiling  water. 
The  plaster,  metal  or  paper  matrix,  when  used,  should  be  removed  first. 
The  base  or  shank  of  the  die  should  be  trimmed  to  the  required  form 
when  necessary. 


Pig.  24. 


The  Swager. — This  is  a  tool  in  which  pieces  of  foil  or  plate  are 
shaped  to  the  form  of  a  die  by  compression,  and  which  may  be  used  as  a 
counter-die  to  a  die  or  vice  versa.  Fig.  24  illustrates  a  swager  partly 
in  section  about  three-fourths  its  actual  size.  A  is  the  cylinder,  B 
the  plunger,  C  cavity  in  plunger  D  cup,  E  base.  The  die  is  mounted 
or  cast  in  the  cup  D,  placed  in  the  base  E,  the  cavity  C  in  the  plunger 
B  is  filled  with  some  compressible  substance  like  moldine,  then  placed 
in  the  cylinder  A  and  the  plunger  struck  down  on  the  die  in  the  cup. 
The  pressure  thus  exerted  by  compression  of  the  material  in  the  plunger 
in  the  direction  of  the  die  gradually  conforms  the  plate  to  its  surface. 


32 


CRGWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


To  mount  a  die  for  swaging  a  disk  of  plate  or  a  gold  cap  in  a  swager, 
fill  the  cup  with  impression  compound  and  insert  the  base  or  shank  of 
the  die  in  it,  as  shown  in  Fig.  25.  A  die  for  the  same  purpose  may  be 
cast  directly  in  the  cup  by  making  an  impression  or  mold  of  the  model 

D 


Pig.   25. — I  C,  Impression  Compound. 

in  the  center  of  the  surface  of  a  fiat  piece  of  moldine,  placing  the  cup 
over  it,  as  shown  in  section  in  Fig.  26,  and  filling  the  cup  through  the 
aperture  with  the  fusible  metal. 

An  intaglio  die  is  made  with  a  cusp  button  by  placing  the  cup  over 
it  and  then  filling  the  cup  with  fusible  metal  (Fig.  27). 


Pig.  26. 


Pig.   27. — D,  Cup;  CB,  cusp  button. 


Swaging. — Cut  the  plate  that  is  to  form  the  matrix  to  the  desired 
shape  and  with  pressure  by  means  of  spunk  or  cotton  approximately 
adapt  it  to  the  metal  model  and  cover  it  with  a  rubber  disk.  Place 
in  the  cylinder  a  mass  of  moldine  about  three-quarters  of  an  inch  thick. 
Insert  in  the  top  of  the  cylinder  the  steel  plunger  and  strike  it  lightly 
with  a  mallet.  Remove  cup  and  model  from  the  cylinder,  examine 
and  burnish  out  any  wrinkles  or  folds  and  reswage. 


CHAPTER  VI 

INVESTMENTS  AND  SOLDERING 

MATERIALS  PRINCIPALLY  USED  FOR  INVESTMENTS — SMALL  INVESTMENTS 
• — LARGE  INVESTMENTS — ASBESTOS — METHOD  OF  INVESTING — PRE- 
PARATION OF  INVESTMENT  FOR  SOLDERING — HEATING  THE  IN\^EST- 
MENT — SOLDERING  BLOCKS — A  SERVICEABLE  AND  LASTING  SOLDER- 
ING BLOCK — THE  STRUCTURE  OF  FLAME — THE  BUNSEN  FLAME — 
THE  BLOWPIPE  FLAME — BLOWPIPE  AND  METHOD  OF  USING  IT — • 
PREPARATION,  APPLICATION  AND  FUSING  OF  SOLDER — SOLDER- 
POINTER — SOLDERING  PRACTICE  DUMMIES  FOR  STUDENTS — OPEN- 
FLAME  SOLDERING — UNION  BY  SWEATING — SOLDERING  WITH  A 
COMPOUND    BLOWPIPE    FLAME — ANNEALING 

Materials  Principally  Used  for  Investments. — Calcined  marble- 
dust  finely  pulverized,  silex,  common  white  sand  or  ground  asbestos, 
combined  in  proper  proportions  with  plaster,  are  principally  used  to 
form  investing  materials  for  crown  and  bridge-work,  as  they  give  a 
small  percentage  of  contraction. 

Small  Investments. — For  small  investments  like  single  crowns,  the 
proportions  generally  used  are  2  parts  finely  pulverized  calcined  marble- 
dust  or  silex  to  i  part  plaster. 

Large  Investments. — For  large  investments,  including  pieces  of 
bridge-work,  i  part  finely  pulverized  calcined  marble-dust  or  silex,  i 
part  sand  and  i  part  plaster.  When  used  in  this  proportion  the  sand' 
prevents  the  excessive  contraction  that  takes  place  in  large  masses  of 
investing  material  composed  entirely  of  fine  marble-dust  when  sub- 
jected to  great  heat  for  considerable  time.  The  fine  marble-dust  in 
combination  with  the  plaster  is  more  suitable  to  fill  in  interstices  and 
the  inside  of  caps  than  the  sand  alone. 

Asbestos. — Asbestos  may  be  substituted  for  sand,  the  coarse  being 
used  in  large  investments.  Trimming  must  be  carefully  done  if 
coarse  asbestos  is  used  as  it  is  not  easily  cut,  and  displacement  of  the 
investment  material  exposing  some  parts  of  the  work  is  liable  to  occur. 

Method  of  Investing. — The  ingredients  should  first  be  thoroughly 
mixed  in  the  dry  state.     Water  is  then  added  in  quantity  sufficient  to 
make  a  thick  batter-like  consistence.     The  thicker  the   mix  can  be 
3  33 


34  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

made  and  be  practical,  the  better.  The  mixture  should  be  rapidly 
and  thoroughly  spatulated.  Potassium  sulfate  may  be  used  in  very 
small  proportion  to  cause  the  mixture  to  set  quickly. 

To  invest  a  model  made  of  investing  material  on  which  bridge-work 
is  being  constructed  the  model  should  be  trimmed  as  small  as  is  safe 
without  risk  of  fracture.  It  should  then  be  soaked  in  water  while  the 
investing  material  is  being  mixed.  The  reduction  of  the  model  is  for 
the  purpose  of  securing  the  largest  possible  proportion  of  refractory 
investing  material  in  the  investment  to  that  of  the  model;  and  its 
immersion  in  water  is  to  prevent  absorption  of  water  from  the  investing 
material  and  to  obtain  a  better  adhesion  of  the  investment  to  the  model. 

In  bridge-work,  especially  in  cases  of  any  great  size,  a  loop  of 
iron  wire  should  encircle  the  piece  in  the  investment.  (See  part  IV, 
Chapter  i.) 

Preparation  of  Investment  for  Soldering. — When  it  is  desirable  to 
remove  the  wax  connecting  sections  of  a  crown  or  bridge  in  an  invest- 
ment before  heating,  it  should  be  done  by  pouring  boiling  water  on  the 
parts.  The  removal  of  wax  with  an  instrument  is  not  advisable,  as 
parts  delicately  held  in  position  are  liable  to  become  displaced.  The 
removal  of  the  wax  exposes  the  metallic  portions  of  the  work  to  be 
soldered.  All  surplus  and  especially  overhanging  investing  material 
should  be  removed,  but  parts  already  soldered  should  be  left  covered. 

The  metallic  parts  to  be  soldered  should  bp  exposed  as  much  as 
possible  to  the  direct  flame  of  the  blowpipe,  as  the  greater  their 
depression  in  the  investment,  the  more  difficulty  will  be  experienced 
in  guiding  and  controlling  the  solder  at  a  particular  point  with  the 
blowpipe. 

Care  should  be  taken  that  all  parts  of  the  porcelain  teeth  are 
covered  and  all  crevices  between  them  filled  with  the  investment  ma- 
terial to  prevent  the  invasion  of  borax  or  solder,  either  of  which  is  very 
liable  to  cause  their  fracture.  The  filling-in  with  gold  foil  of  small 
open  seams  between  sections  of  metal  to  be  united  facilitates  their 
union  in  soldering.  The  filling-in  of  large  spaces  under  caps  or  tips 
to  porcelain  facings  can  also  be  much  facilitated  by  packing  into  the 
spaces  pellets  of  foil  or  by  placing  in  them  pieces  of  plate  or  wire.  A 
moderate  application  of  flux  may  now  be  made  to  the  deeply  invested 
parts,  as  directed  under  article  on  "Flux"  Part  I,  Chapter  II. 

Many  prefer  to  trim  the  investment  and  let  the  wax  burn  out  as  the 
investment  is  heated.  This  is  done  when  fluxed  wax  is  used  and  the 
benefit  of  the  flux  is  to  be  obtained.  The  objection  to  the  burning-out 
of  wax  is  that  owing  to  the  resultant  debris  pits  are  more  liable  to  be 
found  afterward  in  the  solder. 


INVESTMENTS  AND  SOLDERING 


35 


Heating  the  Investment. — In  soldering  crowns  and  bridge-work 
or  sections  of  it  containing  porcelain  facings,  the  investment  should 
be  uniformly,  gradually  and  thoroughly  heated  over  a  Bunsen  flame 
until  the  bottom  of  the  investment  assumes  a  dull  red  tint. 

A  piece  of  heavy  iron  wire,  about  gage  No.  8,  bent  in  the  form  of  a 
scroll,  as  shown  in  Fig.  28,  or  a  piece  of  sheet  iron  perforated  with  large 


holes  placed  across  the  top  of  a  spider  fitted  to  the  burner,  forms  a 
good  support.  When  heated,  the  investment  should  be  removed  to 
a  soldering  block. 

Soldering  Blocks. — A  large  round  piece  of  charcoal  about  5  inches 
in  diameter  and  6  inches  long,  with  a  little  concavity  cut  or  burned  out 
on  one  end,  and  with  a  thin  covering  of  plaster  on  the  sides  to  prevent 
soiling  the  hands,  furnishes  a  good  soldering  support  and  one  that  will 


Pig.  29.. 

retain  the  heat.  Seams  or  cracks  in  the  charcoal  should  be  filled  in 
with  a  mixture  of  sand  or  asbestos  and  plaster,  to  retard  the  burning 
out  of  the  block.  Two  or  three  iron  nails  inserted  in  the  concavity  of 
the  block,  a  little  to  one  side  of  the  center,  are  useful  at  times  to  prop 
up  an  investment.  Manufactured  soldering  blocks,  such  as  are  shown 
in  Fig.  29,  are  preferred  by  many  practitioners  to  those  of  charcoal. 


36 


CROWN-,  BRIDGE;  AND  PORCELAIN-WORK 


Fig.    30. — P,    Plaster;    M, 
mixture;  N,  nails. 


A  Serviceable  and  Lasting  Soldering  Elcck. — Take  a  porcelain  bowl 
about  six  inches  across  the  open  end,  vaselin  the  inside  surface  and 

place  over  it  a  half-inch  coating  of  pure 
plaster.  When  set,  remove  the  plaster 
coating,  which  may  be  facilitated  by  slightly 
warming  the  bowl.  Next  take  equal  pro- 
portions of  coarsely  pulverized  charcoal,  sand, 
asbestos  and  plaster,  a  sufficient  quantity  to 
fill  the  newly  formed  plaster  howl,  and  mix 
together  thoroughly  with  water.  Place  the  mix- 
ture in  the  plaster  cast  of  the  bowl,  slightly  depress  the  center  and  insert 
in  it  four  or  five  iron  nails  to  tilt  the  investment  during  soldering  and 
prevent  it  from  sliding  off  the  block.  (In  section,  Fig.  30.) 
Place  bowl  and  contents  aside  in  a  dry  place  to  set  and 
slowly  dry  out,  which  will  take  some  time.  Before 
using  the  first  time,  thoroughly  heat  the  center  of  the 
surface  of  the  block  with  the  blowpipe  flame. 

This  will  prove  a  very  serviceable  and  durable 
soldering  block  and  one  that  will  hold  the  heat  next  to 
one  entirely  of  charcoal. 


Fig.  31. 


The  Structure  of  Flame 

A  knowledge  of  the  structure  of  flame  will  assist  in  its 
use  in  soldering. 

Fig.  3 1  shows  a  candle  flame.  A ,  central  cone,  consisting  of  unburned 
gases,  termed  non-luminous  cone.  B,  yellow 
cone  of  partial  combustion,  which  emits  the 
light,  termed  the  luminous  cone.  C,  cone 
of  nearly  or  complete  combustion,  which  emits 
only  a  faint  light  and  is  termed  the  semi- 
luminous  cone.  D,  blue  section  of  the  base, 
extending  only  a  short  distance  upon  the  sides. 


A- 


Q 

Fig.  32. 


F.IG.  13. — B,  Central  cone;  C,  deoxidizing  flame;   D, 
oxidizing  flame. 


INVESTMENTS  AND  SOLDERING 


37 


The  Bunsen  Flame. — The  Bunsen  flame  consists  of  a  gas  flame,  into 
the  central  cone  of  which  oxygen  is  carried  by  draft  through  an  aper- 
ture made  in  the  base  of  the  burner,  as  shown 
in  Fig.  32.  The  air  drawn  by  the  draft  of  the 
flame  enters  the  hole  A  and  is  carried  into  the 
central  cone  B,  where  the  oxygen  it  contains 
causes  complete  combustion.  C  is  the  deoxidiz- 
ing or  reducing  flame;  D  the  oxidizing. 

The  Blowpipe  Flame. — The  blowpipe  flame 
differs  from  the  Bunsen  flame  in  that  the  air 
is  forced  into  the  central  cone  of  the  flame 
through  a  central  tube  from  a  bellows  or  air- 
pressure  tank,  Fig.  7,7^.  The  heat  is  intensified 
by  the  complete  combustion  effected  in  the 
Bunsen  and  blowpipe  flames. 

As  shown  in  Figs.  32  and  t^t^,  the  deoxidizing 
flame  is  the  portion  to  be  used  for  soldering,  as 
it  cuts  off  the  oxygen  from  the  air  and  prevents 
oxidization  of  the  metal.  When  an  oxidized 
sheet  of  copper  is  held  in  this  part  of  either  the 
Bunsen  or  blowpipe  flame,  its  surface  is  bright- 
ened in  the  area  of  the  flame.  This  is  caused 
by  the  carbon,  oxygen  and  copper  uniting  and 
forming  carbonic  dioxide,  CO2,  which  is  passed 
off.  The  use  of  the  extremity  of  either  of 
these  flames  should  be  avoided  as  it  naturally 
oxidizes  the  surface  of  the  metal. 

Blowpipe  and  Method  of  Using  it. — A  hand 
gas-blowpipe  (Fig.  34)  operated  by  a  foot- 
bellows  of  medium  size  and  so  constructed  as 
to  be  under  perfect  control,  especially  respect- 
ing diminution  of  the  flame  to  a  very  small 
point,  makes  a  satisfactory  apparatus.  Com- 
pressed air  is  much  used  at  present  in  preference 
to  the  bellows.  When  heated  and  ready  for 
soldering,  place  the  investment  in  the  center  of 
the  soldering  block,  using  large  tweezers  for  this 
purpose.  The  full  flame  of  the  blowpipe  should 
be  directed  at  first  under  and  around  the  sides 
of  the  investment,  which  is  slightly  tipped  or 
propped  up  at  one  side  for  the  purpose.  In  this  manner  the  invest- 
ment is  uniformly  heated  to  a  point  sufficient  to  melt  the  solder 
without  pointing  the  flame. 


Fig.  34. 


38  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

When  the  heat  of  the  surface  of  a  piece  of  metal  is  lower  than  that 
required  to  fuse  the  applied  solder,  the  solder  if  fused  on  it  is  liable 
to  ball  up  and  roll  off.  The  tendency  of  melted  solder  is  to  flow  to  the 
hottest  point.  It  is  also  affected  by  gravitation.  By  the  application 
with  the  blowpipe  of  a  greater -degree  of  heat  under  the  investment  than 
on  the  top,  the  solder  can  be  drawn  down  into  the  deeply  invested 
parts,  but  if  after  flowing  solder  to  and  in  these  parts  a  heat  is  still 
maintained  sufficient  to  keep  the  solder  in  a  molten  condition,  and  a 
slightly  greater  heat  is  applied  to  the  surface  section  of  the  investment, 
the  solder  is  liable  to  be  drawn  upward.  In  the  soldering  of  a  collar 
crown  in  this  manner,  the  solder  that  has  been  drawn  down  between  the 
porcelain  facing  and  cap  and  around  the  collar  on  a  line  with  the  porce- 
lain is  liable  to  be  largely  drawn  backward  and  absorbed  in  the  final 
soldering  of  the  backing  and  contouring  of  the  crown.  Therefore  in 
soldering  the  work,  especially  crowns  and  dummies  with  porcelain 
facings,  these  points  should  be  borne  in  mind.  When  certain  parts  of 
the  work  have  been  united  and  generally  filled  in  with  the  solder  under 
the  effect  of  properly  applied  and  moderate  sized  flame,  the  flame  may 
then  be  reduced  in  volume  and  pointed  for  a  moment  to  guide  the 
solder  to  and  better  shape  it  at  some  special  point.  Proper  position 
for  the  investment  and  correct  application  of  the  heat  in  soldering  aid 
greatly  in  accomplishing  the  desired  result. 

Preparation,  Application  and  Fusing  of  Solder. — The  solder  should 
be  cut  in  small  square  and  oblong  pieces  and  placed  within  convenient 
reach  of  the  points  of  the  tweezers.  The  pieces  may  be  coated  with 
borax  finely  ground  in  water  or  with  liquid  flux,  and  should  be  allowed  to 
dry  before  application  to  the  work.  When  the  investment  on  the  sold- 
ering block  has  been  brought  to  a  dull  red  heat,  or  approaching  it,  with 
the  blowpipe,  a  little  solder  should  be  applied  at  the  point  where  the 
soldering  is  to  be  begun.  The  portion  placed  in  the  investment  is  first 
melted  and  flowed  into  the  insterstices  of  the  work,  using  the  large 
flame  of  the  blowpipe  under  and  around  the  in- 
vestment and  alternately  a  moderately  sized 
flame  at  the  part  being  soldered,  using  the  de- 
A  oxidizing  portion  of  the  flame.     More  solder  is 

'  ■■'    then  added  by  degrees  and,  as  the  parts  become 

Fig.  35.  filled,  by  the  use  of  a  smaller  flame  applied  di- 

rectly to  the  part  and  the  judicious  use  at  times 
of  a  small-pointed  flame  and  the  gradual  addition  of  more  solder  the 
parts  can  be  given  the  desired  form.  Solder  is  also  applied  in  strip 
form.  The  solder  is  cut  in  a  long  narrow  strip  and  one  end  is  held 
while  the  other,  which  has  been  fluxed,  is  applied  to  the  part  being 


INVESTMENTS  AND  SOLDERING 


39 


soldered.  How  to  slit  and  form  the  ordinary  form  of 
solder  into  a  strip  is  indicated  in  Fig.  35,  The  slit  piece 
of  solder  bent  out  is  shown  in  figure  A. 

In  large  pieces  of  bridge-work  with  considerable  curve 
it  will  be  found  necessary  to  solder  a  portion  at  a  time. 
This  is  best  done  by  placing  each  portion  as  it  is  to  be 
soldered  in  the  deepest  part  of  the  concavity  of  the 
soldering-block  and,  when  soldered,  slightly  cooling  and 
changing  the  position  of  the  investment,  as  gravity  tends 
to  carry  the  melted  solder  to  the  lowest  point. 

A  pair  of  solder-tweezers  with  a  long  reach  and  small 
curved  points,  as  illustrated  in  Fig.  36,  should  be  used  to 
pick  up  and  place  the  small  pieces  of  solder. 

Solder-pointer. — A  small  pointed  instrument  with  a 
long  handle,  termed  a  solder-pointer,  is  useful  at  times 
to  stir  up,  spread  and  draw  the  solder  to  a  desired  point. 
The  point  of  the  instrument  should  preferably  be  made 
of  platinum  instead  of  steel. 

When  desirable  to  melt  a  very  small  piece  of  solder  at 
a  point  where  it  is  difficult  to  retain  and  fuse  it  in  posi- 
tion, flux  and  melt  the  desired  quantity  of  solder  in  a 
globule  on  the  block,  and  touch  it  with  the  extreme  tip 
of  the  ''pointer. "  The  globule  will  adhere  to  the  "pointer" 
in  the  form  of  a  little  ball  (Fig.  37).     Heat  the  special 


r 


-zi 


Pig.  37. 


part  to  be  soldered  to  the  fusing  heat  of  the  solder  and 
apply  the  globule  with  the  "pointer. "  When  the  soldering 
is  completed,  an  investment  that  contains  porcelain 
facings  should  be  inverted  on  the  soldering  block  and 
allowed  to  cool  slowly.  This  tempers  the  porcelain  and 
prevents  checking. 

Soldering  Practice  Dummies  for  Students. — The  use 
of  practice  dummy  crowns  and  bridges  affords  an  inex- 
pensive method  of  teaching  students  to  solder.  It  con- 
sists in  cutting  and  shaping  small  pieces  of  German 
silver  or  platinoid  to  represent  the  metallic  parts  of  a 
Pig.  36.      crown  or  bridge,  then  waxing  the  parts  together,  investing 


40 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


and  soldering  them  with  silver  solder,  as  illustrated  in  Fig.  38  (slightly 
enlarged).  A,  shows  a  piece  of  the  metal  bent  to  represent  the  backing 
of  a  porcelain  facing  and  the  floor  of  the  cap  of  a  cuspid  crown;  B  is  a 


Pig.  38. 

side  view  of  the  same  to  indicate  the  angle  at  which  the  metal  should 
be  bent;  C,  the  position  of  the  wax,  the  dotted  line  indicating  the 
surface  of  the  wax;  D,  a  ring  of  the  plate  to  represent  a  molar  crown; 

E  is  a  side  view  of  a  piece  of  plate 
bent  to  represent  the  backing  and 
cusp  cap  of  a  bicuspid  dummy;  F,  a 
lingual  view  of  the  same;  G,  the  line 
of  the  wax. 

Fig.  39  is  a  side  view  partly  in 

section  of  a  dummy  cuspid  crown 

Fig.  40.  invested    and    ready    for   soldering 

practice. 

Fig.  40  represents  a  dummy  bridge  ready  to  solder,  consisting  of  a 

cuspid  and  a  molar  crown  as  abutments  supporting  the  bicuspids. 

Practicing  soldering  on  these  dummies  involves  only  a  trifling 
expense,    and  the  student  will  readily 
acquire  the  technique  and  quickly  be- 
come   proficient   without   waiting   for 
practical  cases. 

Open-Flame  Soldering. — Open- 
flame  soldering  is  done  in  a  Bunsen  (gas) 
flame  and  is  the  method  used  for  sold- 
ering small  sections  of  the  work  such 
as  the  seams  and  floors  of  collars.  A 
Bunsen  burner  of  the  form  illustrated 
in  Fig.  41  (one-half  size)  is  most  con- 
venient for  general  use,  as  it  permits 
the  supply  of  air  to  the  center  of  the 
flame  to  be  regulated. 

The  metal  is  held  by  a  clamp  and  heated  in  the  flame.  (See  part 
III,  Chapter  VI.)  The  heat  should  be  applied  gradually,  with  the 
metal  first  held  above  the  flame  and  then  slowly  brought  downward 


Fig.  41. 


INVESTMENTS  AND  SOLDERING 


41 


into  it  to  a  point  just  above  the  deoxidizing  or  reducing  flame,  and  held 
there  as  briefly  or  as  long  as  is  necessary  to  effect  the  desired  fusion. 

Rouge  in  a  very  thin  paste  or  a  mixture  of  one  part  marble-dust 
and  two  parts  whiting  applied  on  the  inner  or  cavo-surface  of  a  col- 
lar or  cap  will  obstruct  intrusion  of  the  solder.  The  marble-dust  and 
whiting  are  easily  washed  out  but  are  not  as  reliable  a  preventive  as 
the  rouge.  The  heat  should  be  applied  slowly  at  first  to  permit  evapo- 
ration of  the  moisture. 

Union  by  Sweating. — This  consists  in  uniting  the  edges  or  surfaces 
of  two  pieces  of  metal  by  heating  them  so  closely  to  the  fusing-point 
that  union  takes  place  without  melting  the  main  body  of  the  metal. 
The  process  is  much  used  to  unite  the  seams  of  collars.  The  metal  is 
first  boiled  in  acid  and  washed;  the  clean  edges  are  brought  together, 
as  in  the  case  of  a  collar,  so  that  they  lap  slightly,  touching  at  every 
point.  The  edges  are  then  fluxed  and  the  collar  is  placed  on  a  charcoal 
block.  The  whole  of  the  collar  is  first  brought  to  a  bright  red  and  then 
with  a  small  pointed  flame  gently  passed  over 
the  edges  to  be  united  the  gold  is  fused  at  that 
point  and  no  other.  This  is  facilitated  by 
applying  the  flux  only  to  the  parts  to  be 
united,  which  by  preventing  oxidation  causes 
the  surfaces  to  fuse  together  before  the  main 
body  of  the  metal  melts. 

Another  method  is  to  hold  the  collar  with 
a  soldering  clamp,  seam  downward,  in  a 
Bunsen  flame  until  it  unites,  when  it  should 
be  instantly  withdrawn  (Fig.  42). 

Soldering  with  a  Compound  Blowpipe 
Flame. — Platinum  solder  requires  a  compound 
blowpipe  flame  to  melt  it.  This  can  be  impro- 
vised by  connecting  the  air  tube  of  an  ordinary  gas  blowpipe  to  that 
of  a  cylinder  of  nitrous  oxid  gas.  The  flame  of  the  blowpipe  should  be 
reduced  to  a  very  small  jet  and  the  volume  of  the  nitrous  oxid  turned 
on  very  slowly  until  an  amount  of  pressure  is  reached  sufficient  to 
point  the  flame  and  effect  perfect  combustion.  A  small  compound 
blowpipe  of  the  style  illustrated  in  Fig.  43  is  suitable  for  soldering  and 
general  use,^  but  the  fusing  of  platinum  solder  may  be  effected  quite 
satisfactorily  with  the  ordinary  blowpipe,  using  nitious  oxide  instead  of 
air  as  first  described. 

Amiealing. — Annealing  gold  is  done  either  with  the  open  flame,  the 
blowpipe,  or  in  the  muffle  of  a  furnace.     In  the  open  flame  by  holding 

^  The  I.e  Cron  blowpipe. 


Fig.  42. 


42 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


the  piece  of  plate  with  a  clamp  in  the  deoxidizing  part  of  the  flame — 
until  as  high  a  degree  of  heat  is  reached  as  the  character  or  carat  of  the 
plate  will  permit  without  melting.  Pure  gold  will  permit  a  light 
yellow  heat;  i8-  or  2 2 -carat  plate  from  a  dull  to  a  bright  red.  Large 
pieces  of  gold  require  to  be  laid  on  a  soldering  block  and  heated  with  a 
blowpipe. 


Pig.  43. 


Platinum  is  best  annealed  in  an  alcohol  flame  or  in  the  muffle  of  an 
electric  furnace.  It  requires  to  be  brought  to  a  white  heat  and  kept 
there  for  a  short  time.  In  a  gas  flame  platinum  suffers  deterioration 
by  the  formation  of  carbide  of  platinum,  which  oxidizing  later  is  liable 
to  blister  the  metal. 

The  best  results  in  annealing  are  accomplished  by  allowing  the 
metal  to  cool  slowly,  although  much  time  is  often  gained  by  immersing 
in  water.  This,  however,  should  not  be  practiced  with  ingots  of  gold  or 
silver  just  melted  and  poured. 

Each  time  metal  is  bent,  burnished,  hammered,  drawn  or  rolled, 
its  softness,  flexibility  and  ductility  are  impaired,  but  they  are  quickly 
restored  by  annealing.  This  fact  should  be  always  borne  in  mind  in  the 
manipulation  of  metal  in  the  construction  of  all  forms  of  work. 


CHAPTER  VII 

THE  CASTING  PROCESS 

INLAY  WAX^ — FORMATION  OF  THE  INLAY  WAX  MODEL — INVESTMENT- 
INVESTMENT  MATERIAL — HEATING  OF  THE  INVESTMENT — GOLD — ■ 
EXPANSION  AND  CONTRACTION  OF  MATERIALS  AND  METALS — CAST- 
ING MACHINES — CASTING  PROCESS — LARGE  CASTINGS — SCHWEITZER 
WAX  SPRUE  FORMER — EXIT  VENT — LARGE  WAX  MODELS — TO  INSURE 
AGAINST  DISTORTION  OF  THE  WAX  MODEL — TO  CAST  WITH  A 
SWAGER 

The  introduction  in  gold  casting  of  the  process  of  compression  in 
the  construction  of  dental  appliances  has  simplified  and  improved  the 
character  of  many  operations.  Because  it  has  been  comparatively 
recently  introduced,  like  other  innovations  in  dentistry,  the  sphere  of 
its  usefulness  and  whether  it  is  to  be  preferred  to  other  and  longer 
established  methods  are  not  as  yet  definitely  determined.  Practical 
experience  in  time  will  alone  decide.  Many  practitioners,  for  instance, 
who  at  first  used  the  method  extensively  for  plates,  crowns  and  bridges 
have  already  gone  back  to  swaged  plates  and  soldering  operations. 
For  the  formation  of  gold  inlays  and  small  pieces  of  bridge-work  re- 
quiring accuracy  in  form  and  continuity  of  structure,  the  castmg 
process  has  decided  advantages.  But  in  the  casting  of  large  pieces  the 
varying  expansion  and  contraction  of  metal,  wax  and  mold  are  diflacult 
to  entirely  control;  and  the  cast  plate  and  clasp  lack  the  resiliency 
present  in  rolled  gold  plate  or  drawn  wire  attributable  to  the  process 
by  which  they  are  made.  Improvements  in  materials,  and  of  details 
in  methods  of  conducting  operations  may — indeed  already  are  over- 
coming some  of  the  objections  above  outlined  to   casting. 

The  casting  of  gold  from  wax  models  requires  great  accuracy  and 
care  in  all  the  details  of  the  operation,  as  well  as  suitable  materials 
and  appurtenances. 

Inlay  Wax. — Inlay  wax  for  models  is  composed  principally  of  wax 
and  paraffin.     Manufactured  inlay  waxes^  are  supplied  in  sticks  and  in 

1  Manufactured  inlay  wax  is  generally  used  for  inlay  and  other  casting  opera- 
tions. The  exact  composition  of  the  different  inlay  waxes  is  kept  secret  by  those 
manufacturing  them.  Light-colored  pink  hard  sheet  wax  is  often  preferred  by  many 
in  forming  casting  models,  especially  of  saddles  in  crown-  and  bridge-work  construc- 
tion, as  it  can  be  more  conveniently  applied  and  manipulated  than  the  regular 
inlay  wax. 

43 


44 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


cones  or  forms  suitable  for  use  in  cavities  by  casting  the  wax  in  molds 
to  regulate  molecular  tension. 

Formation  of  the  Inlay  Wax  Model. — The  wax  model  is  made 
either  in  the  mouth  or  on  an  anatomically  articulated  model.  The 
former  is  termed  the  Direct  Method  and  the  latter  the  Indirect  Method. 
When  a  casting  is  to  form  part  of  a  crown  or  bridge,  the  shaping  of  the 
wax  model  is  generally  done  on  the  model  on  which  the  work  is  being 
constructed. 

Wax  to  form  a  model  for  casting  should  be  softened  uniformly  in 
warm  water  heated  to  a  temperature  comfortable  to  the  fingers,  which 
ranges  from  120°  F.  to  135°  F.  It  should  be  merely  pressed  to  shape, 
but  not  rolled  or  balled  with  the  fingers.  The  wax  is  first  placed  in 
position  and  then  pressed  with  the  finger,  the  pressure  being  so  directed 
that  the  wax  shall  reach  all  parts  to  be  reproduced,  especially  in  the 
case  of  cavity  walls  and  margins.  The  wax  is  then  trimmed  to  the 
contour  of  the  tooth  with  a  small  spatula.  Every  detail  of  form  and 
finish  desired  in  the  gold  must  be  effected  in  the  wax.  The  wax  model 
should  be  chilled  before  removal. 

For  further  details  in  inlay  work  see  Part  III,  Chapters  XVI, 
XVII,  and  XVIII. 

Adhesion  of  the  wax  to  the  tooth  structure  in  the  mouth  is  prevented 
by  the  saliva  and  on  a  plaster  model  by  wetting  the  part  to  which  the 

wax  is  applied.  When  oil  or  glycerin  is  used 
it  should  be  only  the  smallest  possible  quantity. 
The  warmth  of  the  mouth  prevents  rapid 
hardening  of  the  wax  while  it  is  being  shaped. 
The  same  advantage  may  be  obtained  for  a 
wax  model  in  the  indirect  method  by  placing 
the  entire  case  in  tepid  water  for  a  short  time 
at  intervals. 

Investment. — The  Taggart  investment 
flask  consists  of  a  ring  and  cap  termed  a  crucible  former,  as  shown  in 
section  at  A  in  Fig.  44  (three-fourths  size)  with  the  sprue  wire  B  in 
position.  The  sprue  wire  forms  the  entrance  to 
the  mold  of  the  wax. 

To  invest  the  wax  model  remove  the  sprue  wire 
from  the  cap,  heat  the  point  and  veneer  it  with  a 
particle  of  sticky  wax,  cool  slightly  and  introduce 
the  point  into  the  outer  surface  of  the  wax  model 
at  the  point  of  greatest  bulk  in  the  wax  and  as  far 
as  possible  from  all  margins,  and  at  an  angle  that  will  offer  the  most 
direct  flow  for  the  melted  gold  into  the  mold  of  the  wax.     This  is  shown 


Pig.    44. — A,    Crucible 
former;  B,  sprue  wire. 


Pig.  45. 


THE  CASTING  PROCESS 


45 


in  Fig. 45  (three-fourths  size),  which  illustrates  the  model  of  an  occlusal 
surface  of  a  crown  mounted  ready  to  receive  the  investment.  It  is 
always  best  to  have  the  line  of  any  part  of  the  wax  model  below  the 
point  of  entrance  of  the  sprue  wire  into  the  wax  so  the  molten  gold  on 
entering  the  mold  will  not  be  required  to  take  an  upward  angle. 
A  very  small  sprue  should  be  used  for  extremely  small  castings.  For 
such  cases  it  is  an  advantage  to  fill  the  hole  in  the  crucible  former 
with  wax,  using  a  common  pin  with  the  head  cut  off  for  the  sprue. 

The  surface  of  the  wax  model  should  be  cleansed  before  investment. 
This  is  especially  required  when  oil  has  been  used  to  prevent  adhesion 
of  the  wax,  as  an  oiled  surface  interferes  with  accuracy  of  investment. 
Spraying  the  surface  of  the  wax  with  a  mixture  of  equal  parts  alcohol 
and  ether  will  effectively 
cleanse  the  wax.  Glycerin 
being  readily  soluble  in 
water  is  easily  removed. 
Investment  Material. 
Specially     prepared     in-  Fig.  46. 

vestment  material  is  used 

to  invest  in  casting  work.^  The  material  and  water  should  be 
properly  proportioned  by  weight  and  measure.  Fig.  46  shows  the  Tag- 
gart  device  for  measuring  the  proportion  of  water  and  powder.     It  is 

preferable  to  have  the  mixture 
a  trifle  thick  rather  than  thin. 
A  china  bowl  for  mixing  is  pre- 
ferable to  a  rubber  one,  as  a 
minute  particle  of  rubber  could 
be  scraped  off,  and  freedom 
from  contamination  is  nec- 
essary. The  material  should 
be  swiftly  spatulated  around 
the  sides  for  at  least  a  minute, 
occasionally  jarring  the  bowl  on  the  bench  to  remove  air  and  insure 
a  thorough  mix  (Fig.  47).  A  mixing  apparatus  has  been  introduced, 
but  rapid  continued  manipulation  with  a  spatula  is  effective. 

First  spray  or  wash  the  surface  of  the  wax  with  alcohol  and  ether, 
half  and  half,  to  cleanse  it  especially  of  oil,  then  dip  in  water.     Care- 

^  Prepared  investment  compounds  variously  contain  plaster,  graphite,  whiting, 
silica,  etc.  The  silica  acts  as  a  base,  the  graphite  or  whiting  to  fill  interstices  and 
the  plaster  as  a  binder.  Mr.  L.  J.  Weinstein  gives  his  formula  as  plaster  29  parts, 
fine  silex  71  parts  to  be  mixed  in  the  proportion  of  21  dwt.  (troy),  of  the  powder  to 
one-half  fluidounce  of  water. 


Fig.  47. 


46 


CROWN;  BRIDGE-,  AND  PORCELAIN-WORK 


fully  place  a  thin  layer  of  the  investment  on  the  wax  model  with  a  small 
camel's-hair  brush,  then  larger  portions  until  it  is  covered,  as  shown  in 
Fig.  48.  This  is  to  avoid  air-bubbles,  which  would  fill  with  gold.  Set 
the  ring  on  the  cap  and  carefully  pour  the  remainder  of  the  investment. 
Do  not  jar  the  flask  to  remove  air-bubbles,  for  if  they  are  present  under- 
neath the  wax  model,  they  are  liable  to  settle  against  its  surface  as  they 


Fig.  48. 


Pig.  49. 


are  forced  upward.  Take  time,  as  the  setting  will  not  interfere  with  the 
investing  for  several  minutes.  Do  not  attempt  to  fill  more  than  one 
investment  at  a  time.  Allow  the  investment  to  harden  for  at  least 
twenty  minutes  but  not  for  an  indefinite  time.  If  left  until  the  next 
day  the  mold  before  heating  should  be  placed  in  water  until  saturated, 
to  compensate  for  the  moisture  that  has  dried  out.  When  thoroughly 
set,  remove  the  surplus  investment,  warm  the  flask  slightly  and  remove 
the  crucible  former  and  sprue  wire,  also  any  loose  particles  of  invest- 
ment material.  The  case  is  then 
ready  to  be  heated  for  casting, 
as  shown  in  Fig.  49. 

Heating  the  Investment. — 
This  should  be  done  so  as  to  get 
rid  of  the  wax  model  in  a  manner 
that  will  cause  the  least  possible 
change  in  the  shape  or  dimensions 
of  the  matrix,  and  leave  the  in- 
vestment in  the  best  form  to  cast 
into.  The  flask  is  placed  on  a 
piece  of  sheet  iron  on  a  spider 
over  a  Bunsen  flame,  or  a  support 
such  as  is  shown  in  Fig.  50.  First  the  moisture  of  the  investment 
should  be  evaporated  slowly  at  a  temperature  that  will  melt 
the    wax    but    not    boil   it.     As   the   moisture  is    evaporated,    the 


Pig.  50. 


THE  CASTING  PROCESS  47 

'  investment  gradually  absorbs  the  wax,  leaving  a  clean  matrix 
of  the  model.  •  This  takes  twenty-five  to  thirty  minutes,  the 
heat  being  brought  slowly  up  to  150°  F.,  then  gradually  increased 
as  the  wax  is  absorbed.  The  heat  is  increased  to  a  point  that  will 
volatilize  and  burn  out  the  wax  and  carbonize  any  residue,  which  is 
about  350°  F.,  and  then  to  450°  F.,  allowing  about  fifteen  minutes  for 
the  operation.  In  the  last  few  minutes  the  flask  may  be  placed  on  its 
side  directly  over  the  Bunsen  flame.  The  investment  is  then  ready  for 
the  casting.  Conducted  in  the  manner  outlined,  the  injurious  effect 
of  sudden  or  excessive  heat  is  avoided. 

•  Whether  a  hot  or  a  cool  flask  is  preferable  to  cast  into  is  disputed. 
The  question  is  in  a  measure  answered  by  the  fact  that  the  crucible 
section  of  the  flask  has  to  be  heated  to  the  fusing  point  of  the  gold  in 
the  operation  of  casting. 

The  wax  in  the  mold  at  the  time  it  is  burned  out  leaves  a  film  or 
binder  on  the  wall  of  the  matrix  that  imparts  to  it  a  certain  amount  of 
firmness  and  a  comparatively  unyielding  surface.  This  results  in  a 
smooth  as  well  as  a  bright  casting  by  carbonization  of  the  wax  film 
and  exclusion  of  the  oxygen  of  the  air.  As  this  film  is  greatly  impaired 
by  cooling  and  reheating  the  flask,  the  casting  should  be  done  immediately 
after  the  wax  is  burned  out. 

Gold. — Pure  gold  sHghtly  alloyed  (i  per  cent,  copper)  is  generally 
the  best  for  inlays,  platinized  gold  when  toughness  and  hardness  are 
required,  and  coin  or  21-carat  gold  for  special  parts  of  crown-  or  bridge- 
work.  (See  Part  I,  Chapter  II.)  An  ingot  not  over  three  or  four  dwts. 
more  than  is  required  for  the  casting  is  placed  in  the  crucible.  There 
is  no  waste  of  the  surplus. 

Expansion  and  Contraction  of  Materials  and  Metals. — The  ex- 
pansion and  contraction  of  materials  and  metals  when  heated  and  cooled 
are  difficult  to  determine  and  cannot  be  entirely  overcome.  Therefore 
all  metallic  castings,  though  approximately  correct,  are  not  absolutely 
so.  Inlays  or  other  gold  castings  are  either  expanded  or  contracted 
in  part  or  all  ,of  their  form.  This  is  especially  attributable  to  the 
expansion  and  contraction  of  the  wax;  also  to  the  contraction  of  the 
investment  material  that  forms  the  mold  and  that  of  the  gold.  It  is 
also  caused  by  the  excessive  expansion  of  the  brass  ring  of  the  flask  in 
large  castings. 

Heat  expands  a  wax  model  as  it  is  molded  to  a  given  form,  which 
contracts  as  it  cools.  Investment  material  of  which  a  casting  mold  is 
made  contracts  from  loss  of  moisture.  "This  contraction  is  largely 
counteracted^by;  the  expansion  and  non-shrinking  properties  of  the 


48 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


other  ingredients.     Gold  expands  when  fused  and  contracts  when  it  cools 
(.001451  inch). 

To  meet  these  conditions  the  wax  model  should  be  invested  while  it 
is  warm,  or  if  left  to  cool,  its  temperature  should  be  raised  by  immersing 
it  in  water  of  a  temperature  of  90°  F.  The  temperature  of  the  invest- 
ment should  also  be  brought  to  90°  F.  by  mixing  with  water  of  110°  F. 
The  expansion  of  the  wax  and  some  expansion  also  effected  by  the  use 
of  an  investment  containing  a  proper  proportion  of  silex  will  closely 
compensate  for  the  contraction  of  the  gold. 


Fig.  51. 


Casting  Machines. — Various  forms  of  machines  are  in  use  to  per- 
form the  operation  of  casting.  The  Taggart,  Fig.  51,  the  style  first 
introduced,  melts  the  gold  with  the  carbo-oxyhydrogen  blowpipe  and 
forces  it  into  the  mold  by  pressure  of  the  same  gas.  It  has  two  dial 
indicators,  one  of  which  registers  the  pressure  of  the  gas  in  the  cylinder 
and  the  other  the  pressure  under  which  it  is  released;  a  pressure  valve 
which  can  be  set  for  the  pressure  desired;  a  carbo-oxyhydrogen  blow- 
pipe; a  compressing  lever  and  a  mold  flask  holder. 

The  Jameson  apparatus  uses  centrifugal  force.  The  crucible  is 
mounted  on  an  arm  which  is  swung  in  a  circle  when  the  gold  is  melted. 


THE  CASTING  PROCESS 


49 


The  Price  is  a  centrifugal  machine  which  uses  electricity  to  melt 
the  gold.     The  temperature  is  maintained  in  the  crucible  while  revolv- 


-J^^:^ 


Fig.  52. 


ing  until  the  required  pressure  is  reached  so  that  the  gold  enters  the 
mold  at  full  heat. 

The  Elgin,  illustrated  in  Fig,  52,  is  a  vacuum  machine.  When  the 
gold  has  reached  the  molten 
condition,  a  vacuum  is  created 
under  the  flask  which,  by  the 
porosity  of  the  investment, 
sucks  the  metal  into  the  mold. 

Casting  machines  are  ex- 
tensively used  for  the  compres- 
sion method.  The  gold  when 
fused  in  the  crucible  is  com- 
pressed with  a  wet  asbestos 
packing  that  extends  over  the 
gold  and  flask  disk.  The  steam, 
which  is  instantly  generated, 
forces  the  molten  metal  into 
the  mold. 

The  Platschick,  shown  in  Fig.  53,  also  the  Seymour,  are  of  this 
type. 

The  S.  S.  White  swager,  (Fig.  24)  with  a  specially  designed  casting 
outfit,  is  also  used  for  the  purpose. 


so  CKUW^-,  BRIDGE;  AND  PORCELAIN-WORK 

Casting  Process. — In  the  operation  of  casting,  the  gold  is  placed  in 
the  crucible  cavity  of  the  mold  and  brought  to  a  white  heat,  so  that  it 
appears  to  boil.  The  heat  is  then  lessened  momentarily  sufficiently 
to  allow  the  appearance  of  boiling  to  cease  and  the  gold  is  ready  to  enter 
the  mold.  The  blowpipe  is  instantly  laid  aside  and  the  pressure  applied 
and  retained.  A  pinch  of  pulverized  vitrified  borax  may  be  sprinkled 
over  the  gold  or  its  surface  painted  with  liquid  flux  before  it  is  melted. 
In  the  use  of  a  carbo-oxyhydrogen  blowpipe  a  small  intense  flame 
is  directed  on  the  gold,  which  melts  it  quicker  than  an  ordinary  gas 
flame  and  without  afifecting  the  mold  proportionally.  As  pressure  is 
applied  on  the  molten  gold,  the  residual  air  is  driven  off  into  and  through 
the  minute  pores  of  the  investment.  Superheating  the  gold,  or  ex- 
cessive pressure  in  casting  should  be  avoided.  Superheated  gold  is 
liable  to  unite  with  the  investment  and  excessive  pressure  tends  to 
expand  or  distort  the  investment  matrix. 

In  the  use  of  the  carbo-oxyhydrogen  blowpipe  excessive  heating  is 
liable  to  occur,  owing  to  the  intense  power  of  the  flame.  Excessive 
pressure  can  be  avoided  with  the  Taggart,  as  it  can  be  controlled  with 
the  pressure  valve.  In  other  forms  of  casting  machines  there  is  no 
means  of  definitely  regulating  pressure.  The  pressure  required  for 
casting  is  from  eight  to  ten  pounds  for  large  or  moderate-sized  castings 
and  from  ten  to  thirteen  pounds  for  small  ones.  The  smaller  the  cast- 
ing the  greater  the  pressure  required. 

The  casting  when  cooled  is  removed  from  the  flask  and  scrubbed 
with  a  stiff  brush.  Cut  the  casting  from  the  ingot,  heat  to  a  dull  red, 
drop  into  a  strong  solution  of  sulphuric  acid  or  pure  nitric  acid,  or  both, 

then  wash  and  place  in  hydrofluoric  acid 
for  a  few  hours  or  over  night.  This  gives 
a  clean  surface  to  the  gold. 

Large  Castings. — ^Large   castings  and 

moderately  small  flat  ones  require  one  or 

more  extensions  of    the  sprue  to  better 

enable  the  molten  gold  to  instantly  reach 

all  parts.     Fig.  54  shows  the  model  for  a 

small  plate  so  mounted.     These  extensions 

from  the  sprue  are  made  of  wax  rolled  to  about  the  size  of  the  sprue 

wire.     The  center  of  the  roll  is  attached  to  the  sprue  wire  and  the 

ends  of  the  wax  placed  in  position  on  the  wax  model. 

The  Schweitzer  Wax  Sprue  Former 

In  construction  this  is  a  telescoping  syringe  with  a  small  hole  at 
each  end  by  which  two  sizes  of  wax  sprues  are  quickly  and  easily  formed. 


THE  CASTING  PROCESS 


SI 


To  operate  the  syringe  the  inside  is  charged  with  inlay  wax,  the  syringe 
moderately  heated  and  pressure  exerted  on  the  end  opposite  to  the  one 
from  which  the  required  wax  sprue  is  to  be  ejected  (Fig.  55  in  section). 

Exit  Vent.* — In  large  castings,  a 
vent  that  will  allow  free  escape  of 
vapor  from  the  cavity  of  the  mold  as 
the  molten  metal  is  injected,  facilitates 
and  extends  its  distribution.  Such  a 
vent  is  best  placed  in  the  investment 
above  the  line  of  the  cavity  of  the 
mold.  The  vent  is  made  by  covering 
an  annealed  piece  of  copper  or  iron 
wire  about  gage  No.  ^t,,  with  a  veneer 
of  wax,  then  passing  it  through  a  hole 
in  the  upper  part  of  the  flask  and  bring- 
ing it  down  to  the  wax  model,  as  shown 


V  H 


Fig.  55. — W,  Reservoir  of  wax; 
VH,  vent  holes. 


Pig.  56. — SV,  Sprue  vent. 


in  Fig.  56  (a  Taggart  flask);  or,  the  waxed  wire  may  be  extended 
through  the  surface  of  the  investment  close  to  the  rim  of  the  flask 
down  to  the  wax  model. 

Large  Wax  Models. — To  form  wax  saddle  or  plate  models  for  cast- 
ing, mark  on  the  plaster  model  the  outline  of  the  plate  the  same  as 
for  a  swaging  operation. 

To  harden  the  surface  of  the  plaster,  slightly  dry  the  model  and  give 
the  surface  one  or  two  coats  of  shellac  varnish  well  diluted  with  alcohol 
so  that  it  will  soak  into  the  plaster,  and  allow  it  to  dry.  Next  apply 
one  or  two  coats  of  thin  sandarac  varnish  and  set  the  model  aside  until 
thoroughly  dry.  The  shellac  acts  as  a  binder  and  the  sandarac  glosses 
the  surface.  Vaselin  the  surface  with  a  piece  of  cotton  and  thoroughly 
wipe  it  off.  This  leaves  a  smooth  and  slippery  but  not  a  greasy  surface 
to   the  model.     During  the  formation  of  the  wax  model  or  pattern, 

^  Method  devised  by  Dr.  H.  Schweitzer. 


5-2 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


if  a  lubricant  is  desired,  the  use  of  glycerin  is  preferable  to  oil  or  vaselin 
as  glycerin  is  miscible  in  water  and  consequently  is  easily  washed  ofl 
the  surface  of  the  wax. 

For  the  casting  model  use  thin  sheet  wax,  such  as  is  prepared  and 
sold  for  the  purpose,  or  a  piece  of  semi-transparent  pinkish  wax  now 
used  for  base-plates.  Soften  the  wax  in  tepid  water;  if  too  thick  roll  it 
out  to  the  gage  desired  to  cast  the  plate,  transfer  it  to  the  plaster 
model  and  adapt  the  wax  perfectly  to  its  surface.  Trim  the  surface 
to  the  required  size  as  marked  on  the  model  and  place  a  bead  around 
the  edge,  if  one  is  desired  (Fig.  57). 


Fig.  57. 


Pig.  5f 


The  sprue  wire  should  be  placed  in  position  before  removal  from 
the  model.  It  should  form  a  canal  in  the  investment  through  which 
the  melted  metal  can  flow  directly  and  through  short  wax  sprue 
branches  to  all  parts  of  the  mold.  For  casting  a  large  saddle  the  sprue 
wire  should  be  placed  so  as  to  allow  the  wax  saddle  to  be  set  in  the  flask 
in  a  line  perpendicular  to  the  cavity  of  the  crucible  former,  as  shown  in 
section  in  Fig.  58.  When  set  as  illustrated  the  sprue  wire  may  be 
made  of  a  piece  of  iron  wire  about  gage  No.  14.  In  this  way  a  reliable 
viaduct  is  formed  to  carry  the  gold  to  the  smaller  channels.  An  extra 
long  flask  is  used  to  furnish  space.  The  end  of  the  sprue  wire  is  to  be 
fastened  in  the  hole  in  the  crucible  former  with  hard  wax.  The  wax 
model  is  next  thoroughly  chilled  and  carefully  removed  without  dis- 
tortion of  the  edges.  If  there  is  any  apprehension  that  distortion  has 
occurred,  it  is  best  to  wet  the  plaster  model  and  readjust  the  wax. 
Adhesion  of  the  base  of  the  wax  to  the  model  may  be  avoided  by  first 
adapting  to  the  surface  a  layer  of  thin  gold  foil  and  placing  the  wax 
over  it. 


THE  CASTING  PROCESS 


53 


To  Insure  Against  Distortion  of  the  Wax  Model. — Cover  the  sur- 
face of  the  wax  model  with  a  thick  coating  of  the  investing  material 


Fig.  59. — Three-fourths  actuarsize. 


Pig.  60. 


A 


B 


A 


and  allow  it  to  set.  Next  lift  the  wax  model  and  investing  material 
together  from  the  plaster  model  and  invest  in  the  flask. 

A  saddle  may  also  be  made  of  inlay  wax  by  melting  it  in  a  spoon, 
applying  it  on  the  model  with  a 
brush  and  smoothing  the  surface 
with  a  wax  spatula.  This  is  a 
suitable  method  when  a  model  of 
investing  material  is  used  and 
the  saddle  is  shaped  and  cast 
directly  upon  it. 

When  rubber  is  to  be  vul- 
canized on  the  saddle  or  plate,  to 
connect  the  artificial  teeth,  pieces 
of  platinum  wire  as  attachments 
should  be  inserted  in  the  wax  with 
the  ends  extended  so  that  the  wire 
shall  be  held  in  position  by  the 
investment  in  the  casting.  The 
ends  of  the  cut-off  sprues  left 
after  casting  if  properly  located 
may  also  be  used  for  the  purpose. 

To  Cast  with  a  Swager. — A 
swager,  such  as  the  S.  S.  White 
Dental  Swager,  with  the  acces- 
sories that  accompany  it,  can  be 
used  for  casting.  Wax  models 
for  inlays  or  small  castings  are 
invested  in  the  small  ring,  Fig.  59, 
that   comes  with  the  outfit,  the 

upper  edge  of  which  is  tapered  to  facilitate  quick  adjustment  of  the 
swager.  A  piece  of  wire  about  gage  No.  13  is  used  for  a  sprue.  When 
the  investment  has  set,  cut  with  a  sharp  knife  around  the  sprue  to 
form  a  crucible  for  the  casting  (Fig.  60). 


Fig.  61. 


54 


CROWN;  BRIDGE-,  AND  PORCELAIN-WORK 


Insert  the  plunger  B  of  the  swager  about  one  inch  from  the  lower 
end  of  the  cylinder  A,  Fig.  6i.  Fill  the  depression  C  in  the  plunger 
with  moldine,  extending  it  about  three-fourths  of  an  inch  beyond  the 
end  of  the  plunger.  With  the  thumb  make  an  indentation  I,  in  the 
center  of  the  mass  similar  to  the  depression  C  in  the  end  of  the  plunger. 


Fig. 


62. — Bridge-work    flask 
fourths  actual  size)  . 


(three- 


FiG.  63. 


When  the  investment  R  has  been  dried  out  and  heated  and  is  ready 
for  casting,  set  it  in  the  base  E.  Melt  the  gold  required  for  the  inlay 
in  the  cup  formed  in  the  investment;  heat  to  boiling  point  (white  heat), 
set  the  cylinder  over  the  ring  and  gently  but  firmly  press  the  plunger 
down.  The  time  consumed  in  adjusting  the 
cylinder  is  just  sufficient  to  let  the  boiling  of 
the  gold  cease.  Keep  up  the  pressure  for  at 
least  half  a  minute.  The  pressure  of  air  by 
the  plunger  and  the  steam  from  the  damp 
moldine  combined,  force  the  melted  gold 
into  the  mold. 

For  large  castings  the  flask  illustrated  in 
Fig.  62  made  in  two  sections  as  shown  in 
Fig.  63  (three-fourths  actual  size)  is  used. 
The  open  cup  section  is  of  a  size  to  ac- 
commodate the  application  of  the  swager. 

To  invest  the  wax  model,  remove  the  upper 
cap  and  invest  the  model  in  the  ring,  then  im- 
mediately place  the  removable  cover  over  the  ring,  allowing  the  metal  sprue 
to  project  through  the  center  of  the  opening  in  the  cover,  and  add 
enough  investment  to  fill  to  this  opening.  When  the  investment  has 
set,  treat  it  exactly  as  an  inlay  imbedded  in  a  small  casting  ring,  only 
cupping  up  enough  to  provide  fully  for  the  larger  quantity  of  gold 
to  be  melted.  When  the  investment  is  dried  out  and  heated,  cast  as 
previously  directed. 

Fig.  64  shows  an  invested  saddle  for  a  bridge  in  the  large  flask. 


Fig.  64. 


CHAPTER  VIII 


FINISHING  PROCESS 


FINISHING    AND   POLISHING — ELECTRO-PLATING 

Finishing  and  Polishing. — The  preparatory  or  preliminary  dressing 
off  of  gold  should  be  done  with  small  carborundum  wheels  and 
points,  first  coarse  and  then  fine,  on  the  dental  engine.  This  method 
is  preferable  for  this  part  of  the  work  to  the  use  of  files  or  the  lathe. 

First  trim  and  finish  interdental  spaces  and  fissures.  Thin  vulcan- 
ized rubber  and  carborundum  wheels  and  sandpaper  disks  are  service- 
able for  the  purpose.  Narrow  interdental  and  wash 
spaces  are  most  effectively  reached  with  pumice 
by  applying  it  on  a  cotton  cord.  Fasten  one  end  of 
the  cord  to  the  bench  and  holding  the  other  end 
with  the  left  hand  draw  the  bridge  back  and  forth 


Pig.  65. 

on  the  cord  with  the  right  hand  (Fig.  65) .  Next  polish  the  easily  reached 
surfaces  with  pointed  or  flat  felt  cones  with  pumice  and  water  or  some 
other  preferred  polishing  material.  Then  go  over  the  entire  bridge  with  a 
brush  wheel,  using  fine  pumice  and  soap  until  the  surfaces  are  rendered 
perfectly  smooth.  Apply  the  soap  by  holding  a  piece  of  it  against  the  re- 
volving bristles  for  a  moment.  Wash  off  all  the  soap  and  pumice  and  for 
the  final  finish  use,  whiting  or  rouge  applied  with  polishing  wheels  on 
the  lathe.  Then  thoroughly  wash  the  bridge  with  warm  water.  As  a 
holder  for  an  all-gold  crown  while  polishing,  trim  a  piece  of  wood,  about 
four  or  five  inches  long  and  one-half  inch  wide  and  shape  the  end  to  fit 
closely  into  the  crown  for  use  as  a  handle.     A  piece  of  heated  impression 

ss 


56 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


compound  placed  on  the  end  of  the  stick  and  inserted  in  the  crown 
will  additionally  secure  it.  Fig.  66  shows  a  crown  holder  that  catches 
inside  the  crown. 

Electro-plating 

The  surfaces  of  the  different  grades  of  gold  composing  a  crown  or 
bridge  can  be  rendered  uniform  in  color  and  more  resistant  to  oxidation 
and  discoloration  by  plating  with  pure  gold.  A  plating  outfit  is 
readily  constructed  as  described  below.  A  plating  solution  to  use  with 
it  consists  of: 

CUoride  of  gold M  oz. 

Cyanide  of  potassium i      oz. 

Water 8      oz. 


Of 


Fig.  67. 

The  plating  outfit  is  illustrated  in  Fig.  67.  The  base  (A)  is  a  J;;^  in. 
board,  i  foot  long  by  8  inches  wide.  The  upright  piece  (B)  is  9  inches 
high  by  6  inches  wide.  Two  carbon  globes  (C)  are  placed  at  one  end, 
and  the  jar  (D)  for  the  solution  at  the  other.  For  a  no-volt  direct 
current  use  a  no- volt  i6-candle-power  lamp  and  a  220- volt  32-candle- 
power  lamp  placed  in  series  to  reduce  the  current.  The  wires  are  first 
connected  to  the  plugs  (E).     The  positive  current  is  passed  through 


FINISHING  PROCESS  57 

the  two  lamps  and  the  negative  current  transmitted  direct  to  the  so- 
lution. The  wires  pass  through  the  two  small  holes  (FF)  in  the  upright 
board  (B).  Two  hooks  (GG)  are  inserted  under  the  holes.  The 
negative  wire  is  connected  to  one  and  the  positive  to  the  other  at  the 
shanks  of  the  hooks  as  they  are  screwed  into  the  board.  On  the  posi- 
tive side  suspend  in  the  solution  a  piece  of  pure  gold  plate  (H)  rolled 
very  thin;  the  upper  end  of  the  plate  is  held  by  a  clamp  supported  on 
the  hook  to  which  the  negative  wire  is  attached.  The  article  to  be 
plated  (I)  is  held  by  a  piece  of  copper  wire  looped  over  the  hook  con- 
nected with  the  positive  wire.  The  positions  of  the  positive  and 
negative  wires  are  distinguished  the  one  from  the  other  by  first  testing 
the  current  with  the  plating  solution  by  the  use  of  a  two-piece  plug 
and  changing  its  position  in  the  socket.  When  the  position  of  the 
poles  is  determined  the  plug  can  be  marked  for  future  correct  insertion. 
Before  plating,  the  metal  should  be  trimmed,  smoothed  and 
polished,  using  pumice  and  whiting  or  rouge,  and  then  boiled  in  a 
solution  of  lye  and  washed  in  warm  water. 


PART  II 

PREPARATORY  TREATMENT  OF  TEETH  AND 
ROOTS  FOR  CROWN-  AND  BRIDGE-WORK 


PREPARATORY  TREATMENT  OF  TEETH  AND  ROOTS  FOR 
CROWN-  AND  BRIDGE-WORK 

GENERAL  CONSIDERATIONS 

Preparatory  to  crown  and  bridge  operations  the  mouth  should  be 
put  in  the  healthiest  possible  condition.  The  teeth  should  be  first 
scaled  of  any  calculus  present,  then  cleaned  and  polished.  Roots  or 
teeth  incurably  affected  should  be  removed,  pyorrhea  and  any  existing 
lesions  treated  and  cured;  also,  such  measures  should  be  adopted  as 
will  prevent  the  recurrence  of  old  troubles  or  the  inception  of  new. 

Notwithstanding  all  that  advanced  knowledge  of  therapeutic 
agents  and  skill  in  their  use  permit,  there  are  many  teeth  and  roots 
which  cannot  be  rendered  suitable  for  the  successful  apphcation  of 
crown-  and  bridge-work.  Roots  which  are  permeated  and  softened  by 
decay,  exposed  or  loosened  by  absorption  of  the  gingivae  and  alveoli, 
or  affected  by  irremediable  disease  of  the  investing  membranes  should 
be  thus  classed.  Cases  in  which  abscess  with  necrosis  has  extensively 
impaired  the  walls  of  the  alveoli  are  equally  intractable. 

Experience  shows  that  the  results  in  this  department  of  dentistry 
depend  largely  upon  diathesis  or  constitutional  tendency  and  upon  the 
attention  given  to  the  preservation  of  the  health  of  the  mouth.  These 
conditions  should  be  carefully  estimated  in  the  selection  of  a  system  of 
treatment  and  the  method  of  its  application. 


CHAPTER  I 
THE  PULPS  OF  TEETH 

PREPARATORY   PROCESSES — DISINFECTION   OF   VITAL   DENTIN       * 

The  preservation  of  the  vitality  of  the  pulps  of  the  teeth  or  their 
extirpation  in  crown-  and  bridge-work  is  a  subject  that  requires  careful 
consideration. 

The  excision  of  natural  crowns  for  the  purpose  of  utilizing  their 
roots  for  artificial  crowns  as  abutments  for  bridge-work  is  extensively 
practiced,  and  is  defended  on  the  theory  that  the  vitality  of  the  dentin 
is  to  an  extent  maintained  by  the  cementum  after  the  extirpation  of  the 
pulp,  or  that  the  pulp,  being  the  formative  organ,  is  of  no  further 
value  in  a  fully  developed  tooth  when  root-canal  treatment  is  properly 
conducted. 

The  pulp  after  going  through  the  progressive  changes  which  con- 
stitute its  original  function  assumes  a  fixed  anatomical  character  as  the 
source  of  the  vascular  and  nervous  supply  from  which  the  dentin 
derives  and  maintains  its  vitality.  The  protoplasmic  bodies  of  the 
pulp  unite  with  the  living  matter  of  the  tubuli,  which  anastomose  to  a 
limited  extent  with  those  of  the  cementum  through  the  intervening 
protoplasmic  bodies  in  the  interzonal  layer. 

This  distribution  and  relative  connection  of  living  matter  refers  to 
an  existing  state  of  perfect  vitality  of  all  the  parts.  When  the  pulp 
loses  its  vitality,  an  entirely  different  condition  results.  The  tubuli 
are  then  deprived  of  vital  circulation,  except  along  the  lines  of  the 
outer  portion  of  the  dentin,  where,  in  the  interzonal  layer,  the  fibrillse 
anastomose  with  the  living  matter  of  the  cementum.  The  vitality 
supported  by  this  anastomosis  is  insufficient  to  take  over  the  functions 
of  the  pulp  and  maintain  circulation  in  the  main  body  of  the  dentin. 
(See  Plate  I.) 

When  the  pulp  has  been  removed,  the  devitalized  fibrillae  still 
remain  and,  unless  antiseptic  root-canal  treatment  is  thoroughly 
carried  out,  their  disintegration  generates  septic  gases  capable  of 
producing  irritation  of  the  cementum  and  pericementum.^ 

^  The  analysis  of  dentin  by  Dr.  G.  V.  Black  gives  an  average  of — 

Lime-salts 63 .  54 

Organic  matter 25 .  36 

Water 11 .06 

Age  slightly  lessens  the  proportion  of  living  matter  and  increases  the  percentage 
of  lime-salts. 

63 


64 


CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 


An  examination  of  the  investing  membranes  of  many  pulpless  teeth 
shows  the  existence  through  ineffective  treatment  of  a  percentage  of 
abnormal  conditions,  by  which  their  firmness  is  to  an  extent  impaired, 
their  susceptibility  to  acute  imflammation  increased,  and  their  re- 
habihty  as  foundations  for  crown-  and  bridge-work  greatly  lessened 
a^  compared  with  teeth  which  have  living  pulps.  Frequently  such 
conditions,  when  found  in  evidence  in  connection  with  the  work  of 
some  of  our  best  operators,  are  attributable  more  to  difficulties  that 
interfered  with  the  perfect  performance  of  root  treatment  than  to 
carelessness  or  lack  of  skill. 


Plate    I. — L,  Lacunae  of  the  cementum;    C,    canaliculi  of  dentin;   I,   interzonal 

layer — X  210. 


Observation  also  has  shown  that  the  dentin  of  gold-capped  pulpless 
natural  teeth  in  the  course  of  years  gradually  softens  sufficiently  to 
impair  their  strength.  Again,  on  the  other  hand,  the  extirpation  of 
pulps  permits  a  better  performance  of  details  of  operations,  such  as  the 
shaping  of  natural  crowns  for  crowning  or  for  utilization  as  supports 
for  bridges;  and  the  advantages  thus  gained  are  in  the  opinion  of  many 
proportionately  of  greater  consideration  than  that  of  pulp  conservation. 
Additionally,  as  the  dentin  calcifies  as  years  advance,  the  proportion 
of  living  matter  in  it  becomes  gradually  less;  therefore  the  older  the 
patient  the  less  pulp  extirpation  has  to  be  seriously  considered. 


THE  PULPS  OF  TEETH 


65 


A  general  study  of  the  subject  will  show  many  methods  of  practice 
that  will  properly  permit  pulp  preservation  and  in  contra-distinction 
also  indicate  where  a  preferable  condition  will  be  insured  by  pulp 
removal. 

Preparatory  Processes 

That  extirpation  of  the  pulp  and  excision  of  the  natural  crown, 
especially  of  an  incisor  or  cuspid,  will  at  times  simplify  the  work  and 
permit  better  forms  of  construction  is  undeniable.  Besides,  the  ques- 
tion of  root-canal  treatment  is  not  to  be  as  seriously  considered  in 
relation  to  anterior  as  to  posterior  teeth  where  its  perfect  performance 
is  not  so  easy  of  accomplishment.  When  the  removal  of  the  entire 
enamel  and  a  large  portion  of  the  dentin  of,  for  instance,  a  bicuspid  or 
molar  tooth,  is  necessary  to  properly  shape  it  for  a  collar  or  cap-crown, 
the  removal  of  the  pulp  is  usually  demanded  and  should  precede  the 
operation;  otherwise,  irritation  of  the  dentinal  tubuli  is  liable  to  follow 
and  consequent  lesions  of  the  pulp.     In  such  cases,  as  the  future  of  the 


Fig.  68. 

tooth  depends  on  the  effectiveness  of  the  canal  treatment  that  the 
circumstances  will  permit,  it  is  advisable  to  take  a  radiograph  that 
shows  the  form  and  condition  of  the  roots  and  canals.  Cases  such  as 
are  illustrated  in  Fig.  68  present  difficulties  that  suggest  the  advisa- 
bihty  of  resorting  to  the  use  of  the  most  favorable  method  of  bridge 
construction  that  will  permit  retention  of  the  pulp  in  an  abutment 
tooth;  as  a  larger  percentage  of  trouble  results  from  ineffective  root- 
canal  treatment  than  from  normal  pulps  degenerating  under  crown  or 
inlay  operations. 

Pulps  which  are  in  normal  condition  and  still  protected  by  a  layer 
of  partly  decomposed  dentin  usually  admit  of  successful  treatment.  In 
such  cases  the  decayed  dentin  should  be  thoroughly  excavated  from 
the  side-walls  of  the  cavity,  but  that  over  the  pulp  need  be  only 
superficially  removed. 

Extirpation  is  always  demanded  for  pulps  in  a  pathological  condition 
or  whose  permanent  preservation  cannot  be  placed  beyond  doubt,  as 


66  CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 

failure  involves  more  serious  consequences  in  crown-  and  bridge-work 
than  in  filling  operations. 

The  lesions  of  the  pulp  that  require  its  extirpation  are,  all  forms  of 
exposure,  congestion  and  pulpitis  which  does  not  yield  promptly  to 
remedial  treatment. 

Disinfection  of  Vital  Dentin. — When  decay  has  extensively  involved 
the  dentin  and  closely  approached  the  pulp,  as  a  precaution  against 
subsequent  irritation,  thorough  disinfection  of  the  dentin  and  any 
remaining  decomposed  portion  which  may  have  been  left  over  the 
region  of  the  pulp  is  advisable. 

The  method  of  disinfection  is  to  first  thoroughly  wash  the  cavity 
several  times  with  tepid  water  thrown  gently  from  a  syringe  around  the 
sides  of  the  cavity;  then,  taking  measures  to  prevent  the  entrance  of  the 
saliva,  wipe  the  cavity  with  absorbent  cotton  and  pass  over  its  surface 
a  light  current  of  hot  air  from  a  hot-air  syringe.  The  heat  should  be 
suflScient  to  cause  some  discomfort  to  the  patient  but  not  enough  to 
produce  irritation  of  the  pulp.  The  dried  cavity  is  then  immediately 
saturated  with  carbolic  acid  previously  warmed  to  the  normal  tem- 
perature of  the  body  by  holding  the  pellet  of  cotton  on  which  it  is 
applied  over  the  flame  of  a  lamp  for  a  moment.^  The  carbolic  acid 
relieves  any  pain  caused  by  the  evaporation  of  moisture  and  disinfects 
and  sterilizes  any  decomposed  matter  in  proximity  to  the  pulp.  The 
object  of  the  application  of  the  carbolic  acid  having  been  accomplished, 
the  surplus  may  then  be  removed  from  the  surface.  To  this  end  the 
cavity  should  first  be  wiped  with  absorbent  cotton  and  hot  air  again 
introduced  to  evaporate  the  moisture  sufficiently  to  give  a  dry  appear- 
ance to  the  surface  of  the  dentin.  This  second  application  of  hot  air, 
owing  to  the  effect  of  the  carbolic  acid,  will  cause  little  or  no  pain. 

This  method,  if  practiced  early  in  the  preparation  of  the  cavity, 
will  be  found  to  considerably  obtund  sensation,  and  through  the  dryness 
secured,  to  materially  facilitate  the  removal  of  the  decomposed  dentin. 
For  excavating  in  the  region  of  the  pulp  chamber,  spoon-shaped  excava- 
tors should  invariably  be  used.  For  the  thorough  disinfection  of 
dentin  and  the  removal  of  hypersensitive  conditions,  the  author  prac- 
tices the  method  of  previously  placing  and  sealing  in  the  cavity  for 
from  two  days  to  a  week  a  mixture  of  precipitated  chalk,  carbolic  acid 
and  oil  of  cloves  in  equal  parts.  A  small  quantity  of  aristol  may  also 
be  added. ^ 

1  Thermal  shock  to  the  pulp  is  as  unwarranted  from  the  application  of  cold 
carbolic  acid  as  if  produced  in  any  other  manner. 

2  The  chalk  is  placed  in  a  mortar,  and  the  carbolic  acid  and  oil  of  cloves  gradually 
introduced  and  thoroughly  incorporated  with  the  chalk  by  trituration  until  the 
mixture  becomes  a  plastic  mass. 


THE  PULPS  OF  TEETH  67 

The  disinfected  dentin  over  the  pulp  is  next  varnished  with  cloro- 
gutta-percha  or  some  other  preparation  suitable  for  the  purpose,  and 
capped  with  oxyphosphate.  When  the  capping  is  set,  the  remainder 
of  the  cavity  is  filled  with  the  same  cement  as  the  capping  or  with  an 
inlay  or  amalgam.  The  rubber-dam,  when  its  use  is  practical,  should 
always  be  applied  in  these  operations.  The  shaping  of  the  coronal 
section  of  a  tooth  for  a  crown  or  the  preparation  of  the  cavity  for 
an  inlay  can  then  be  proceeded  with.  In  the  latter  case  the  cement  can 
be  trimmed  as  though  it  were  dentin,  leaving  enough  to  fully  protect 
the  pulp. 


CHAPTER  II 
DEVITALIZATION  OF  THE  PULP 


INSTANTANEOUS  DEVITALIZATION — USE  OE  COCAIN,  CATAPHORESIS  AND 
PRESSURE  ANESTHESIA — EXCISION  OF  THE  CROWN  AND  INSTANTANE- 
OUS  EXTIRPATION   OF   THE  PULP — DEVITALIZATION    WITH   ARSENIC 

When  devitalization  is  necessary  in  preparation  for  crown- work  two 
methods  are  practiced :  the  heroic — instantaneous  devitalization — and 
gradual  devitalization  by  arsenical  treatment. 

Instantaneous  Devitalization. — This  is  accomplished  by  first  open- 
ing into  the  dentin  or  cavity  in  the  direction  of  the  pulp  (Fig,  69),  then 

administering  to  the  patient  sufiicient 
nitrous  oxid  to  produce  anesthesia  and 
with  a  drill  quickly  exposing  and 
lacerating  the  pulp  well  up  the  canal 
with  a  probe  or  smooth  broach.  In- 
stantly afterward  a  pellet  of  cotton 
saturated  with  carbolic  acid  is  forced 
up  the  canal  and,  if  possible,  left  until 
the  next  day,  when  the  pulp  will  be 
found  in  a  coagulated  mass  that  is 
easily  removed  entire. 
Use  of  Cocain,  Cataphoresis  and  Pressure  Anesthesia. — In  cases 
of  actual  exposure  of  the  pulp  and  those  in  which  the  patient  permits  its 
exposure  by  removal  of  the  decay  or  the  use  of  a  small  spear-shaped 
drill,  the  rubber-dam  is  appHed,  the  exposed  pulp  obtunded  with 
adrenahn  and  cocain  (Parke,  Davis  &  Co.,  Hypodermic  Tablets  No. 
115)  in  tablets  appHed  in  saturated  solution.  The  diffusion  may  be 
hastened  by  electrolysis. 

Pressure  anesthesia  is  effected  by  first  removing  a  small  portion  of 
the  enamel  in  the  direct  line  of  the  pulp,  then  piercing  the  dentin  with 
a  fine  spear-shape  drill  as  deeply  as  possible  without  causing  excessive 
pain.  The  cocain  solution  is  then  introduced  on  a  few  fibers  of  cotton 
placed  in  the  hole  drilled.  Pressure  is  next  exerted  on  the  solution  with 
a  ball-shaped  burnisher  on  a  pellet  of  unvulcanized  rubber  inserted 
in  the  cavity.     The  pressure  should  be  directed  in  the  line  of  the  pulp. 

68 


Pig.  69. 


DEVITALIZATION  OF  THE  PULP 


69 


As  soon  as  the  action  of  the  cocain  is  manifested  the  drilling  should  be 
continued  and,  if  necessary,  the  solution  again  applied.  The  solution 
is  to  be  gradually  worked  into  the  pulp  as  soon  as  it  is  exposed,  with  a 
fine  smooth-pointed  broach;  or  injected.  After  the  lapse  of  two  or 
three  minutes  the  pulp  can  be  painlessly  extirpated. 

Excision  of  the  Crown  and  Instantaneous  Extirpation  of  the  Pulp. 
— This  is  performed  as  follows:  Two  parallel  grooves  are  cut  through 
the  enamel  opposite  to  each  other  and  deep  into  the  dentin,  one  on  the 
labial  portion  of  the  tooth  and  the  other  on  the  lingual  wall,  close  to  the 
gingiva,  with  a  rapidly  revolving  carborundum  or  vulcarbo  disk  (Fig. 
70).    The  crown  is  then  severed  from  the  root  with  excising  forceps  (Fig. 


Pig.  70. 


Pig.  71. 


Fig.  72. 


71).  The  pulp  either  adheres  to  the  excised  crown,  leaving  the  canal 
empty,  or  remains  in  the  root  fully  exposed.  In  the  latter  case  a  pointed 
piece  of  orange  wood,  previously  cut  to  fit  the  canal  and  saturated  with 
carbolic  acid,  is  driven  with  a  quick  blow  into  the  pulp  towards  the  apex 
of  the  root  (Fig.  72),  When  the  wood  is  withdrawn  the  pulp  usually 
adheres  to  it,  but,  if  not,  the  wood  is  instantly  reinserted,  cut  off  and 
drilled  out  with  the  pulp,  using  Gates-Glidden  drills  in  the  upper 
portion  of  the  canal. 

Expertly  performed  this  operation  is  advantageous.  It  should, 
however,  be  confined  to  teeth  the  pulps  of  which  are  in  a  normal 
condition.  Practical  experience  shows  that  in  such  cases  it  is  attended 
with  the  most  satisfactory  results.  Only  trifling  pain  is  felt  by  the 
patient,  as  the  pulp  is  paralyzed  by  shock  in  the  excision  of  the  crown 
or  by  being  forced  upward  towards  the  foramen  and  against  the  walls 


70  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

oi  the  canal.  This  method  however  is  seldom  practiced  since  the  in- 
troduction of  the  use  of  cocain. 

The  subsequent  vitality  of  the  cementum  is  assured  by  the  instan- 
taneous procedure  in  pulp  extirpation,  and  discoloration  of  dentin  and 
enamel  is  minimized  as  much  as  possible,  but  when  the  natural  crown 
is  utilized  in  bridge  operations,  the  translucence  of  the  teeth  is  usually 
impaired  by  pulp  removal. 

Devitalization  with  Arsenic. — The  methods  of  devitalization  pre- 
viously described  are  most  successfully  applied  to  normal  or  only 
sHghtly  calcified  pulps.  Pulps  of  teeth  extensively  calcified,  molars 
especially,  do  not  so  well  permit  the  instantaneous  methods.  Con- 
sequently recourse  at  times  is  had  to  arsenical  treatment  with  highly 
nervous,  sensitive  patients,  notwithstanding  the.numerous  objections  to 
its  use.  Two  theories  as  to  the  mode  of  its  action  in  devitalizing  are 
widely  entertained:  First,  that  its  toxic  effects  produce  hyperemia, 
which  stops  circulation;  second,  thrombosis.  This  theory  of  throm- 
bosis might  account  for  the  gradual  devitalization  of  the  pulp  toward 
the  foramen. 

Whatever  the  action  of  arsenic  on  the  pulp  may  be,  it  causes  some 
infiltration  of  the  tubuli  of  the  dentin  with  certain  constituents  of  the 
blood,  probably  the  liquor  sanguinis.  To  an  extent  the  residue  of  the 
infiltration,  after  the  devitalization  of  the  pulp,  remains  in  the  tubuli, 
increasing  the  difficulty  of  producing  an  aseptic  condition  of  the  dentin 
and  proportionately  causing  its  discoloration.  This  discoloration  is 
most  marked  when  arsenic  is  applied  to  dentin  over  an  unexposed 
pulp.  It  is  asserted  that  arsenic  sometimes  afifects  the  vitality  of  the 
cementum  by  its  diffusion  to  the  zone  around  the  apex  of  the  root. 

Arsenic  when  used,  should  be  applied  directly  to  the  pulp  in  the 
smallest  quantity  possible  to  effect  devitalization,  and  securely  sealed 
in  the  cavity.  In  cases  of  non-exposure  requiring  its  application,  a 
small  opening  into  the  pulp-chamber  if  possible  should  be  made.  This 
can  be  accomplished,  as  already  described,  with  but  little  pain  to  the 
patient. 

Arsenic  may  be  combined  with  creosote  or  carbolic  acid  in  the 
smallest  possible  proportion  of  the  arsenic  that  will  effect  devitahzation, 
or  with  agents  which  are  non-coagulants  of  albumin.  Dr.  Harlan's 
method  to  avoid  using  coagulants  of- albumin  is  to  apply  an  anodyne, 
such  as  wine  of  opium,  for  a  minute  or  two,  and  then  the  following 
paste: 

I^.  Arsenous  acid,  3i 

Muriate  of  cocain,        3ij 
Lanolin  in  quantity  sufficient  to  make  a  stiff  paste. 


DEVITALIZATION  OF  THE  PULP  ^i 

No  arsenical  application  should  be  kept  in  position  longer  than  is 
necessary  to  effect  devitalization  of  the  pulp,  twelve  to  forty-eight 
hours  being  sufficient.  The  short  period  refers  to  a  case  in  which  there 
is  no  calcification  and  application  is  made  in  direct  contact  with  the 
pulp.  The  longer  periods  are  where  the  application  is  not  quite  direct, 
or  where  the  pulp  is  slightly  or  considerably  calcified.  The  pulp- 
chamber  is  then  opened,  a  saturated  solution  of  tannin  in  glycerin 
applied  and  securely  sealed  in  the  cavity,  and  the  patient  dismissed  for 
a  day  or  two  when,  in  favorable  cases,  the  pulp  can  be  removed  entire. 


CHAPTER  III 

PULPLESS  TEETH 

REQUIREMENTS  OF  TREATMENT — PREPARATION  OE  ROOT-CANALS — REAM- 
ING— TREATMENT — USE  OE  ANTISEPTICS — CLOSURE  OE  THE  APICAL 
FORAMEN   AND   FILLING   OF   THE   CANAL 

Requirements  of  Treatment. — The  treatment  of  pulpless  teeth  or 
roots  consists  in  as  thorough  performance  as  possible  of  the  following 
procedures: 

First:  Proper  opening  up  and  enlargement  of  the  canal  to  the  fora- 
men and  removal  of  the  contents. 

Second:  Antisepsis  of  the  root-canal  and  dentin  and  the  establish- 
ment of  permanent  aseptic  conditions  by  mummification  of  the  contents 
of  the  tubuli. 

Third:  Closure  of  the  apical  foramen  and  prevention  of  future  in- 
fection from  the  oral  cavity  by  the  hermetical  closure  of  the  entrance 
to  the  canal. 

Preparation  of  Root-Canals. — A  knowledge  of  the  usual  form  and 
position  of  the  roots  and  of  the  different  teeth  and  the  orifices  and  lines 
of  the  root-canals  (See  Plate  II  and  Figs.  130  to  138  inclusive)  is  essential 
for  a  generally  successful  performance  of  this  operation.  The  proce- 
dure is  greatly  simplified  since  the  introduction  and  use  of  radiographs 
that  definitely  show  the  length  and  form  of  the  roots  and  canals  to  be 
operated  on,  as  well  as  any  abnormality  present.  The  direct  access 
in  the  line  of  the  root-canals  that  is  obtainable  in  crown  operations 
greatly  facilitates  the  work  of  effective  treatment. 

In  all  cases,  in  the  preliminary  removal  of  tooth  structure  sufficient 
of  the  crown  should  be  left  to  easily  permit  the  application  of  the 
rubber-dam  and  the  retention  of  dressings  with  gutta-percha  seals. 
When  teeth  are  broken  down  or  extensivel}^  decayed  beyond  the  gum 
margin  and  hypertrophied  gum  tissue  invades  the  cavity,  the  diseased 
tissue  should  be  removed,  the  cervical  section  of  the  margin  of  the 
cavity  excavated  and  an  antiseptic  dressing  applied. 

The  cavity  should  then  be  packed  with  gutta-percha  well  anchored 
either  against  the  adjoining  tooth  or  in  the  orifice  of  the  pulp  cavity  in 

72. 


PULPLESS  TEETU 


73 


a: 


/ 


74 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


such  a  manner  as  to  stop  hemorrhage  and  press  back  the  tissue  slightly 
beyond  the  edge  of  the  cavity  and  expose  it  for  the  next  stage  of  the 
treatment,  as  shown  in  a  case  of  approximal  decay  in  Fig.  73  and 
decay  on  both  sides  in  Fig.  74.  In  cases  where  the  side  wall  of  a 
tooth  is  so  far  decayed  under  the  gum  margin  as  to  render  application 
of  the  rubber-dam  either  extremely  difficult  or  impracticable,  a  thin 
collar  or   matrix  may  be  adapted  to  the  peripheral  sections  and  ce- 


FiG.  73. 


Pig.  74. 


Fig.  75. 


men  ted  in  position  with  oxyphosphate  cement,  as  shown  in  Fig.  75.  D 
indicates  the  cervical  line  of  decay.  When  the  cement  has  set,  the 
rubber-dam  is  applied  and  enough  of  the  cement  removed  with  a 
bur  to  expose  the  pulp  cavity  and  permit  the  root-canals  to  be  treated 
and  filled.  The  collar  may  remain  on  during  the  treatment.  When 
treatment  and  root-canal  fillings  are  completed,  the  cavity  inside  the 


Pig.  76.  Pig.   77. — Sectional  view  of   an  inferior 

molar  decayed  on  the  posterior  approximal 
side.  A.  The  line  to  which  the  crown 
should  be  removed  to  facilitate  entrance  to 
the  pulp-chamber. 

collar  can  be  filled  vs-ith  amalgam  or  first  lined  with  oxyphosphate  and 
the  amalgam  inserted  while  the  oxyphosphate  is  still  soft.  When  the 
amalgam  has  set  the  collar  is  removed. 

In  the  preliminary  treatment  of  an  infected  pulpless  tooth  a  fine 
probe  should  always  be  inserted  in  the  root-canal,  to  be  withdrawn 
when  the  temporary  filHng  is  completed,  to  leave  a  vent  for  the 
escape  «f  gases.  Pressure  should  be  exerted  with  an  instrument  on  the 
temporary  filling  to  prevent  its  displacement  as  the  probe  is  with- 


PULPLESS  TEETH  75 

drawn.  First  remove  the  tooth  structure  over  the  pulp-chamber  in  the 
direct  line  of  the  canal.  Where  the  coronal  section  of  a  normal  incisor 
or  cuspid  is  to  be  preserved,  operate  from  the  lingual  side,  Fig.  76. 
The  removal  of  the  coronal  section  of  teeth  directly  exposes  the  pulp- 
chamber.  In  bicuspids  and  molars  for  an  all-gold  crown,  the  occlusal 
surface  and  the  side  walls  of  the  cavity  should  be  removed,  to  give 
direct  access  to  the  canals  (Fig.  77).  The  pulp-canal  of  an  incisor  or 
cuspid  is  easily  reached;  bicuspids  and  molars  are  more  complicated. 
When  the  buccal  roots  of  the  superior  molars  join  together,  the  canals 
incline  to  a  similar  condition,  and  in  the  third  molars  the  buccal  and 
lingual  canals  occasionally  unite  and  form  one  large  canal.  These  are 
conditions  that  are  usually  indicated  to  the  operator  by  the  radio- 


PlG.  78.    • 

graph.  In  the  case  of  the  superior  molars,  the  canal  of  the  palatal 
root  is  the  first  that  should  be  located,  and  in  the  inferior  molars  the 
canal  of  the  distal  root.  By  locating  these  canals  in  normal  cases,  the 
others  can  more  easily  be  found.  In  cases  of  extensive  calcification 
frequently  the  orifice  of  each  canal  must  be  separately  located.  If  the 
orifice  of  a  canal  is  not  apparent,  endeavor  to  locate  it  with  a  pulp- 
canal  pick  (Fig.  78)  by  prodding  the  dentin  in  the  expected  location. 
If  calcification  has  only  partly  closed  it,  prodding  with  force  will 
usually  disclose  it.  If  the  orifice  is  entirely  closed,  remove  some  of  the 
dentin,  guided  by  a  radiograph,  and  again  apply  the  pick.  When 
entrance  to  the  canal  has  been  effected,  probe  it  with  a  fine  sharp 
pointed  broach  to  determine  its  direction  and  length.  Next  enlarge 
the  orifice  with  a  cone-shaped  bur  or  a  Gates-Glidden  drill  (Fig.  79) 
so  as  to  give  it  a  funnel  shape  to  guide  the  points  of  instruments  into 
the  canal. 

For  effective  root-canal  treatment  the  operator  should  be  equipped 
with  a  full  set  of  the  most  approved  broaches,  root-canal  files,  drills, 


76 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


and  reamers  for  use  both  in  hand  and  engine  (Figs.  79,  80,  81.  82  and 

83)- 

The  orifice  of  the  canal  having  been  opened  up,  if  a  devitalized 
pulp  is  present,  remove  it  with  a  fine  Donaldson  barbed  broach  by 


Pig.  79. 


12      3      4      5     6 

XIP  XF    F     M     0    XC 

Style  B 

Pig.  82. 


i 


Pig.  80. 


Pig.  81. 


1     2     3    4     5    6     7,    8     9    10  11  12 
XXF  XP    P     M    C     XC 

Fig.  83. — Root  Canal  Reamers. 


passing  the  broach  as  far  up  the  canal  as  possible,  then  entangling  the 
pulp  on  the  barbs.  This  is  best  done  by  moving  the  broach  a  little 
upward  and  downward  and  twisting  it  slightly  in  the  downward  move- 
ment. Next,  guided  by  frequent  explorations  with  a  fine  pointed 
broach  (Fig.  80),  the  canal  is  carefully  enlarged  with  Kerr's  root-canal 


PULPLESS  TEETH 


77 


files  (Fig.  82)  and  Donaldson  broaches  (Fig.  81).  They  should  be  used 
delicately  with  an  up-and-down  motion,  beginning  with  the  smallest 
first  and  then  increasing  in  size. 

A  75-per  cent,  aqueous  solution  of  sulfuric  acid  carried  on  a  fine 
platinum  probe  to  the  canal,  then  pumped  into  it  with  a  small  broach,  is 
most  effective  as  an  aid  in  opening  up  very  small  canals  or  those  partly 
closed  by  calcification.  In  the  former  case  the  acid  softens  the  dentin 
of  the  sides  of  the  canal  so  that  the  friction  of  a  smooth  broach  will 
materially  enlarge  it.  In  the  latter,  in  addition  to  this  effect,  it  de- 
composes the  calcified  contents  of  the  canal.  The  enlargement  of  the 
canal  with  a  smooth  broach  permits  the  introduction  of  root-canal 
files  and  Donaldson  barbed  broaches,  first  small  and  increasing  in  size,  by 


Fig.   84. — Radiographs  showing  wires  in  root-canals. 

which  the  canal  can  almost  invariably  be  safely  opened  and  enlarged 
to  the  zone  of  the  cementum  and,  when  alveolar  abscess  exists,  through 
the  foramen.  When  so  opened,  they  can  be  thoroughly  divested  of 
organic  matter  by  the  action  of  the  acid  and  use  of  the  broaches. 

The  application  of  acid  in  root-canals  of  normal  teeth  should  not  be 
carried  further  than  the  zone  of  the  cementum  at  the  apex,  for,  should 
it  penetrate  the  foramen  and  reach  the  pericementum,  it  is  liable  to 
cause  irreparable  injury  to  that  membrane.  When  the  acid  has  ac- 
compHshed  its  purpose  it  should  be  removed  and  its  further  action 
neutralized  by  sodium  bicarbonate  solution. 

A  canal  should  be  slightly  enlarged  to  the  foramen  to  facilitate  root- 
canal  filling,  but  not  through  to  the  apical  space  except  when  an  ab- 
scess is  present.  The  depth  to  which  a  canal  is  or  has  been  penetrated 
can  be  determined  by  the  insertion  of  a  metallic  wire  into  the  canal 
and  then  taking  a  radiograph  with  the  wire  in  position.  This  is  re- 
peated as  often  as  is  deemed  necessary  during  the  operation  (Fig. 84). 


78  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

It  should,  though,  be  borne  in  mind  that  divergence  of  a  broach  from 
the  Hne  of  a  canal  is  indicated  according  to  the  angle  the  radiographic 
rays  have  been  cast.  Accordingly,  any  divergence  of  a  broach  in  a 
canal  in  either  a  lingual,  labial  or  buccal  direction  is  not  always  as 
certainly  determined. 

When  a  canal  has  been  penetrated  and  slightly  enlarged  with 
root-canal  files  or  broaches,  apply  Gates-GHdden  drills  (Fig.  79)  or 
reamers  (Fig.  83)  from  a  small  to  a  large  size,  as  the  case  requires.  The 
distance  a  reamer  should  be  used  up  a  canal  and  the  size  of  the  reamer 
are  regulated  by  the  form  and  size  of  the  root  and  whether  or  not  the 
canal  is  to  carry  an  anchorage  post. 

Reaming,  with  hand  reamers  or  with  Gates-Glidden  drills — which  are 
practically  reamers — and  the  engine,  should  be  done  with  a  slight  up- 
and-down  movement  as  they  are  revolved  and  with  very  little  pressure 
apphed.  Under  too  much  pressure  the  instrument  might  be  broken 
off,  or  in  a  straight  root  be  forced  through  the  foramen.  Nor  should 
reamers  be  forced  into  canals  closed  by  calcification  or  into  a  curved 
root.  A  slight  pain  is  usually  experienced  under  normal  conditions 
when  they  enter  the  zone  of  sensibility  formed  by  the  cementum  which 
composes  the  end  of  the  root,  of  the  slightest  symptom  of  which  the 
patient  should  be  instructed  to  instantly  inform  the  operator.  The 
probe-like  points  of  the  Gates-Glidden  drills  do  not  cut  but  simply 
guide  the  drills  and  confine  them  to  the  line  of  the  canal.  They  should 
be  frequently  sharpened  with  an  Arkansas  stone  of  knife-blade  form. 
An  occasional  quick  withdrawal  of  the  drill  from  the  canal  during  the 
process  of  drilling  will  aid  the  removal  of  the  debris. 

Moderate  reaming  of  a  root-canal,  in  addition  to  simplifying  the 
operation  of  filling,  opens  up  the  ends  of  the  tubuli  and  facilitates  the 
permeation  of  antiseptic  agents.  Opening  up  root-canals  evidences  the 
skill  of  the  operator  and  when  effectively  performed  and  associated  with 
correct  filling  insures  the  success  of  the  operation. 

Occasionally  a  root-canal  is  so  small  and  the  end  of  the  root  so 
shaped — as  indicated  by  the  radiograph — that  enlargement  of  the  canal 
to  the  extremity  of  the  apex  is  hazardous,  because  liable  to  involve 
perforation  of  the  root,  especially  when  advanced  or  entire  calcifica- 
tion is  present.  In  such  cases,  especially  in  entire  calcification  of  the  canal 
showing  no  lesion  of  the  apex,  the  canal  should  be  opened  up  as  far  as 
practical  and  the  remainder  rendered  inert  by  mummification  with 
repeated  dressings  of  antiseptics.  The  canal  is  then  filled  and  the  ori- 
fice hermetically  closed.  When  a  root  is  very  small  or  the  end  curved — 
as  indicated  by  a  radiograph — in  the  former,  reaming  should  be  pro- 
portioned to  the  size  of  the  root,  and  in  the  latter  it  should  carry  only  as 


PULP  LESS  TEETH  79 

far  as  the  curve  will  safely  permit.  In  both  cases  the  remainder  of  the 
canal  can  then  be  enlarged  with  root-canal  files  and  broaches. 

In  a  case  of  entire  calcification  and  obliteration  of  the  canal,  the 
center  of  the  root  should  be  opened  up  in  the  line  of  the  track  formerly 
occupied  by  the  pulp,  with  round  burs  proportioned  in  gage  to  the 
former  canal  and  in  depth  as  far  as  is  safe  without  risk  of  penetration 
of  the  side  of  the  root  or  apex.  The  dentin  is  then  mummified  by 
applications  of  a  saturated  solution  of  aristol  in  the  essential  oils,  re- 
peated at  intervals  of  three  or  four  days,  until  the  dentin  is  darkened 
in  shade,  indicating  its  thorough  permeation.  The  canal  is  best 
entirely  filled  with  zinc  oxychlorid. 

Treatment. — Pulpless  teeth  are  presented  for  treatment  in  one  of 
the  four  following  conditions: 

1 .  Where  the  normal  pulps  have  just  been  extirpated  from  the  canals. 

2.  Where  on  opening  into  the  pulp-chamber,  the  pulp  is  found 
partly  or  entirely  calcified  in  the  canals  with  little  or  no  vitality  and  the 
root  externally  in  a  healthy  condition. 

3.  Where  the  pulp  is  found  diseased  or  in  a  putrescent  condition. 

4.  Where  alveolar  abscess  is  present  and  a  septic  condition  of  the 
canals  and  dentin  exists. 

In  the  first  and  second  classes  the  treatment  should  be  directed 
to  assuring  a  continuance  of  the  existing  aseptic  condition  and  the 
filling  of  the  canal;  in  the  third  and  fourth  classes,  to  bringing  about  an 
aseptic  condition  by  disinfection  and  sterilization  and  making  certain  of 
its  future  maintenance,  including  incidentally  the  cure  of  any  existing 
disease  of  the  external  membrane  of  the  alveolus. 

In  cases  of  the  first  and  second  classes,  if  possible,  saliva  should  be 
excluded  from  the  pulp-chamber  and  canals  during  their  entire  prepara- 
tion and  filling.  If  necessary  to  syringe  out  the  canal,  alcohol  can  be 
used  instead  of  water.  The  instruments  should  be  sterilized  and 
broaches,  if  serrated,  had  better  be  new.  In  the  third  and  fourth 
classes,  exclusion  of  saliva  or  water  is  not  necessary  in  the  preliminary 
work  on  the  canal;  and  water  may  be  freely  used  until  the  process 
of  disinfection  and  sterilization  is  commenced,  after  which  its  entrance 
should  be  prevented.  To  this  end  the  rubber-dam  should  be  applied 
if  practicable.  When  not,  as  frequently  occurs  with  roots  and  teeth 
badly  affected  with  cervical  decay,  they  should  be  treated  as  shown 
in  Fig.  75,  or  other  means  of  keeping  out  moisture  be  resorted  to.  In 
such  cases,  when  the  rubber-dam  is  not  applied  and  cotton  rolls  are 
used,  during  each  interruption  of  the  operation  the  entrance  to  the 
canal  should  be  packed  with  absorbent  cotton  saturated  with  alcohol, 
the  saliva  being  thus  excluded. 


8o 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


In  cases  of  the  third  class  in  opening  up  the  canal  great  care  should 
be  taken  not  to  force  any  of  the  septic  matter  through  the  foramen 
and  cause  infection  of  the  apical  space.  This  is  frequently  difficult 
to  avoid;  so,  as  a  precautionary  measure,  at  first  open  up  only  the  ori- 
fice of  the  canal,  then  introduce  and  inclose  in  it — leaving  a  vent — anti- 
septic agents  until  its  contents  are  rendered  inert. 

After  the  canal  has  been  properly  opened  up  and  its  contents 
removed,  it  is  washed  out  with  alcohol  and  wiped   with   absorbent 

cotton,  and  is  then  ready  for  further 
treatment.  The  use  of  sodium  potassium 
is  recommended  by  Dr.  E.  C.  Kirk  at  this 
stage  as  a  germicidal  saponifier  and  to 
open  up  the  ends  of  the  tubuli,  but,  as  in 
the  use  of  sulfuric  acid  in  normal  cases  it 
should  not  be  allowed  to  reach  the  zone  of 
the  cementum.  The  next  procedure  is 
to  secure  as  thorough  a  state  of  dryness  in 
the  pulp-chamber  as  is  possible,  by  forcing 
into  it  hot  air  with  a  hot-air  syringe,  (hand 
or  electric),  at  a  temperature  higher,  as  it 
leaves  the  nozzle,  than  is  comfortable  for 
the  finger.  A  root-canal  drier  with  a 
tapered  point  may  then  be  introduced  into 
the  canal,  preferably  with  the  point  of 
silver  and  the  bulb  of  copper  (Fig.  85). 
As  silver  possesses  remarkable  properties 
as  a  thermal  conductor,  the  heat  is  trans- 
mitted to  the  point  of  the  probe  very 
rapidly.  The  probe  being  inserted  as  far  as  possible  up  the  canal 
(Fig.  86),  the  patient  is  directed  to  raise  the  hand  as  a  signal  should 
the  heat  cause  pain,  in  which  case  the  probe  must  be  moved  up  and 
down  or  withdrawn  for  a  moment.  This  procedure,  following  the 
previous  application  of  the  hot  air  with  the  syringe,  evaporates  the 
moisture  and  aids  the  escape  of  any  gases  present  in  the  root-canals 
and  the  open  ends  of  the  tubuli. 

The  point  of  the  root-canal  drier  acts  as  a  sterilizer  and  may  be 
applied  so  hot  as  to  carbonize  any  organic  matter  which  it  reaches  in  the 
end  of  the  canal,  a  portion  of  which  may  be  removed  each  time  on  its 
point.  As  the  silver  point  can  be  tapered  as  small  as  the  finest  broach, 
canal  contents  impossible  to  entirely  remove  may  be  reached  and  ren- 
dered inert. ^ 

1  Use  introduced  by  the  author  in  1887  and  use  of  hot-air  published  in  article  in 

the  Herald  of  Dentistry  in  1 884. 


Fig.  85. 


PULP  LESS  TEETH  8i 

In  cases  of  the  third  or  fourth  class,  sepsis  being  present,  the  heat  is 
very  serviceable,  as  it  aids  the  escape  of  gases  from  the  canal  and  dentin 
and  acts  as  a  germicide.  When  in  this  dry  and  heated  condition  the 
dentin  is  in  the  best  possible  state  for  the  application  of  antiseptic 
agents. 

Use  of  Antiseptics. — Great  diversity  of  opinion  exists  as  to  the 
suitability  of  various  antiseptics  in  treating  tooth-structure,  their 
effectiveness  and  permanency  when  so  used,  whether  singly  or  in 
combination,  and  their  adaptability  to  various  conditions.  Many  of 
the  antiseptics  in  common  use,  being  coagulants  of  albumin,  obstruct 
the  dentinal  tubuli  and  their  diffusibility  through  the  dentin  is  conse- 
quently retarded.  To  this  class  belong  carbolic  acid,  creosote  and  the 
like.  They  are  not  entirely  non-diffusible  in  devitalized  dentin  or  ce- 
mentum,  as  decomposition  effects  elementary  changes  in  the  contents 
of  the  tubuli,  but  their  action  is  slow  and  limited  as  compared  with  that 
of  some  other  agents,  as  the  essential  oils.  The  former  are  also  irritants 
and  unsuitable  in  cases  where  an  acute  or  chronic  inflammation  of  the 
peridental  membranes  is  to  be  treated. 

Formalin  in  the  form  of  Formocresol  is  recommended  by  Drs.  Kirk 
and  Inghs.  There  is  no  question  as  to  the  efficiency  of  formalin,  but  on 
account  of  its  irritant  properties  it  should  be  used  with  great  caution. 
It  should  not  be  introduced  up  the  canal  as  far  as  the  zone  of  cementum 
at  the  apex  and  a  vent  shoul  dbe  left  in  the  filling  placed  over  it  suffi- 
ciently large  to  permit  free  escape  of  the  formalin  gas  into  the  oral 
cavity  instead  of  being  forced  up  in  an  apical  direction. 

The  essential  oils,  which  are  non-coagulative  in  their  action,  have 
greater  diffusibility  and,  according  to  Miller,  Harlan  and  others,  possess 
much  greater  antiseptic  power  than  was  formerly  attributed  to  them. 
For  this  reason  the  essential  oils  in  combination  with  preparations  of 
iodin  that  exert  a  chemical  action  and  retain  their  antiseptic  properties 
for  a  great  length  of  time,  are  the  most  approved. 

The  selection  of  antiseptic  agents  is  therefore  important,  and  the 
choice  is  indicated  by  the  conditions  presented  in  a  pulpless  tooth. 
A  tooth  from  which  a  healthy  pulp  has  just  been  extracted  with  the 
canal  in  an  aseptic  condition  differs  in  its  requirements  from  a  case  in 
which  sepsis  of  dentin  or  a  diseased  or  putrescent  pulp  is  present. 

In  the  first  mentioned  conditions  favorable  results  usually  follow 
root  filling,  with  or  without  antiseptic  treatment,  the  advantage  of  the 
antiseptic  agent  in  the  canal  being  to  better  assure  the  continuance  of 
the  state  of  asepsis.  When  a  healthy  pulp  has  just  been  extirpated 
and  immediate  root  filling  is  practiced,  the  use  of  carbolic  acid  or  creo- 
sote is  indicated.     The  minute  fibrous  connections  with  the  wall  of  the 


82  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

canal  and  the  vessels  at  the  apical  foramen  are  severed  and  the  action 
of  an  escharotic  antiseptic  agent  is  in  fact  required,  as  it  acts  as  a  coagu- 
lant and  instantly  seals  up  the  ends  of  the  tubuli.  If  immediate  root 
filling  is  not  to  be  practiced,  then  the  prescription  of  such  agents  as  the 
essential  oils  with  aristol  or  iodoform  seems  suitable,  as  by  their  action  a 
sort  of  mummification  of  the  non- vital  organic  matters  follows.  More- 
over, the  oils  possess  advantages  over  the  coagulants  in  that  they  are 
not  miscible  in  water  and  are  less  easily  eliminated.  Their  use  will  tend 
better  to  perpetuate  an  aseptic  condition. 

In  the  second  class  of  cases,  also  in  teeth  of  the  third  and  fourth 
classes  with  sepsis  of  dentin,  or  diseased  or  putrescent  pulps,  we  need 
the  intervention  of  agents  which  will  not  only  destroy  ptomaines  but 
which  will  exert  a  chemical  action  on  sulfureted  hydrogen  and  ethereal 
ammoniacal  gases,  the  products  of  putrefaction,  and  entirely  eliminate 
them.  On  this  depends  the  successful  treatment  of  such  cases,  for  until 
disinfection  of  the  dentin  is  absolutely  accompHshed  the  canal  is  not 
in  a  suitable  condition  to  be  closed.  Carbolic  acid,  creosote  or  the 
essential  oils,  under  such  circumstances,  exert  no  chemical  action  on 
these  gases,  merely  disguising  their  odor,  though  it  is  true  that  by 
repeated  dressings  of  cotton  saturated  with  one  of  these  agents,  the 
gases  are  absorbed  by  the  cotton  and  slowly  eliminated. 

What  is  required  is  the  action  of  disinfecting  agents  whose  elements 
possess  an  affinity  for  these  gases  and  so  will  immediately  decompose 
them,  forming  new  combinations  and  entirely  changing  their  character. 

In  accordance  with  this  principle,  iodin  is  indicated  as  preferable  to 
the  other  agents  mentioned.  Its  effects  are  best  obtained  from  some  one 
of  the  preparations  in  use,  preferably  aristol  (dithymolbiniodid)  from 
which  nascent  iodin  is  liberated,  the  odor  of  which  is  not  objectionable, 
in  a  strong  or  saturated  solution  in  one  of  the  essential  oils.  In  practice 
the  oils  of  cloves,  cassia,  myrtol  and  eucalyptol  are  favored  for  this 
purpose,  the  first  named  being  reckoned  more  sedative  in  its  action 
than  the  others.  The  canal  should  be  flooded  with  the  solution, 
thereby  to  some  extent  permeating  the  dentin,  as  well  as  the  cementum 
at  the  apex.  A  more  complete  saturation  can  be  accomplished  by 
drying  and  heating  the  dentin  and  applying  the  solution  several 
times,  or  by  filling  the  canal  with  cotton  saturated  with  it,  hermetically 
closing  it  and  letting  it  so  remain  for  a  day  or  two. 

As  aristol  in  combination  with  oil  of  cloves  or  cassia  has  a  tendency 
to  slightly  discolor  dentin,  its  use  should  be  confined  to  the  extremity 
of  the  root-canal  and  plain  oil  of  eucalyptol  or  myrtol  used  in  the 
orifice  and  coronal  section  of  the  tooth  where  maintenance  of  the 
natural  shade  of  the  crown  is  to  be  considered  in  an  operation.     When 


PULP  LESS  TEETH  83 

a  normal  pulp  has  been  extirpated  from  an  anterior  tooth  and  the 
crown  is  to  be  preserved  intact  and  its  shade  maintained,  oil  of  myrtol 
should  alone  be  used;  and  the  foramen  within  a  day  or  two,  if  not 
immediately,  should  be  closed  with  gutta-percha  and  the  canal  filled 
with  zinc  oxychlorid. 

The  disadvantage  of  immediate  root  filling  is  that  should  some 
minute  fragment  of  the  pulp  remain  in  the  extremity  of  the  canal,  it 
fails  to  receive  the  benefit  accruing  from  the  reapplication  of  antisep- 
tics, which  would  better  assure  its  inertness  by  mummification. 

In  the  treatment  of  a  root-canal  from  which  a  pulp  has  just  been 
removed  or  when  no  pathological  condition  exists  at  the  apex,  an  acute 
inflammation  of  the  pericementum  of  that  part  is  frequently  produced 
from  the  applied  antiseptic  agent  being  pressed  or  pumped  through  the 
foramen  and  invading  the  apical  space.  Such  cases  are  relieved  by 
washing  out  the  canal  with  alcohol,  applying  the  alcohol 
as  a  dressing  and  tightly  sealing  the  entrance  to  the 
canal  with  oxyphosphate  cement  for  a  few  days.  To 
avoid  such  an  inflammation  the  author  at  first  applies 
the  essential  oil  diluted  with  alcohol  or  chloroform. 
The  solution  is  applied  on  cotton, — 'from  which  all  excess 
is  removed, — gently  packed  in  the  canal  and  sealed  with 
cement  for  a  day  or  two.  At  the  next  treatment  the 
foramen  and  only  the  extreme  end  of  the  canal  are  pj,,  g 
closed  with  gutta-percha  as  shown  at  GP,  in  Fig.  87. 
The  treatment  can  then  be  continued  and  the  antiseptic  be  applied 
with  safety  in  full  strength. 

The  dressing  of  root-canals  is  best  performed  with  the  aid  of  ordi- 
nary smooth  flexible  rectangular  broaches,  and  with  root-canal  dress- 
ers. The  form  of  these  instruments  permits  fibers  of  cotton  to  be 
easily  wound  around  them  lengthwise  and  over  the  point  in  one  con- 
nected mass.  When  the  cotton  is  introduced  in  the  canal,  it  is  retained 
on  and  carried  forward  by  the  instrument  which,  when  withdrawn, 
leaves  the  cotton  in  position  in  the  canal  in  the  form  of  a  cone  or  tampon 
that  in  septic  cases  will  favor  the  escape  of  gases  and  may  still  be 
easily  removed  at  any  time  After  one  or  several  treatments  in  the 
manner  described,  between  which,  if  intervals  of  time  are  to  elapse, 
the  antiseptic  agents  must  be  hermetically  sealed  in  the  cavity  with 
gutta-percha  or  oxyphosphate  or  a  small  quantity  of  gutta-percha 
covered  with  oxyphosphate.  When  the  treatment  is  completed  the 
canal  is  dried  and  the  foramen  closed,  if  this  has  not  already  been 
done,'and  the  canal  filled. 


84  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Closure  of  the  Apical  Foramen  and  Filling  of  the  Canal. — The 

object  of  root-canal  filling  is  the  maintenance  of  an  aseptic  condition 
in  a  sterilized  root-canal  by  hermetically  closing  it  at  both  the  apical 
foramen  and  the  orifice,  thus  preventing  its  infection  by  the  entrance 
of  either  fluids  or  gases.  Gutta-percha  to  close  the  foramen  and  fill  the 
extremity  of  the  canal  and  zinc  oxychlorid  to  fill  the  remainder  and  the 
orifice  are  generally  accepted  as  most  suitable. 

The  extreme  end  of  the  canal  is  first  pumped  full  of  chloro-gutta- 
percha  with  a  broach  or  small  probe,  and  any  surplus  towards  the 
orifice  of  the  canal  absorbed  with  cotton.  A  cone  of  solid  gutta- 
percha of  suitable  size  to  fill  the  upper  third  of  the  canal  is  then  inserted 
and  pressed  into  the  chloro-gutta-percha.  The  cone  is  best  carried  to 
^  position  by  heating  the  point  of  a  small  root-canal  plugger 

and  attaching  the  cone  on  the  point,  as  shown  at  A, 
Fig.  88.  The  cone  is  then  placed  and  gently  pressed  but 
not  suddenly  pushed  into  position  in  the  canal  and  de- 
tached from  the  plugger  by  giving  the  plugger  a  sudden 
twist.  The  gage  of  the.  point  of  the  plugger  used  should 
always  be  larger  than  the  foramen  so  as  to  avoid  the 
risk  of  pushing  the  point  through  in  packing  the  gutta- 
PiG  88  percha.  A  current  of  hot  air  is  next  thrown  on  the 
protruding  end  of  the  cone  at  a  temperature  sufficient  to 
soften  it  and  warm  the  dentin,  when  it  should  be  again  gently  pressed  up 
the  canal.  A  slight  twinge  of  pain  to  the  patient  will  usually  be  the 
signal  of  its  complete  impactment  in  the  end  of  the  canal.  The 
solid  gutta-percha  absorbs  what  little  chloroform  is  present,  the  heat 
then  evaporates  the  chloroform  and  the  pressure  condenses  the  gutta- 
percha. If  the  process  of  heating  and  condensing  is  repeated  suffi- 
ciently, the  gutta-percha  can  be  solidly  condensed.  Its  shrinkage 
is  thus  reduced  to  a  minimum  or  entirely  overcome. 

The  advantages  possessed  by  zinc  oxychlorid  over  other  materials 
are  its  antiseptic  qualities  and  its  density.  Its  disadvantages  are  its 
tendency  to  produce  irritation  when  pumped  into  or  through  a  foramen, 
and  the  difficulty  attending  its  removal  from  the  extremity  of  the 
canal,  should  conditions  require  that  course.  These  objections  are 
removed  by  filling  the  upper  third  of  the  canal,  as  described,  with 
gutta-percha.  The  remainder  of  the  canal  and  the  pulp-chamber  are 
filled  with  the  oxychlorid.  To  effect  this  proportion  of  the  oxychlorid, 
remove  any  excess  of  the  gutta-percha  present  from  the  orifice  and 
lower  section  of  the  canal  with  a  round-headed  bur  as  shown  at  B. 
The  oxychlorid  should  be  mixed  very  thin,  carefully  pumped  up  the 
canal  and  compressed  with  an  instrument  or  cotton  as  it  sets  (C).    . 


PULP  LESS  TEETH  85 

The  combination  of  gutta-percha  and  zinc  oxychlorid  forms  an 
ideal  root-canal  filling,  as  the  zinc  oxychlorid  hermetically  closes  the 
orifice  of  the  canal  and  prevents  its  infection  from  the  oral  cavity. 

When  metallic  points  of  lead  or  copper,  shaped  to  fit,  are  used  to 
fill  root-canals,  unless  a  small  quantity  of  chloro-gutta-percha  is  first 
placed  in  the  extremity  of  the  canal,  the  complete  closure  of  the  foramen 
is  doubtful.  The  best  method  is  to  close  the  foramen  with  gutta- 
percha, pump  up  the  canal  a  thin  mixture  of  zinc  oxychlorid  and  then 
insert  the  metallic  point. 

The  use  of  cotton  as  a  filling  in  root-canals  is  to  be  condemned. 
A  few  fibers  of  iodoformized  cotton'  may  be  used  as  a  vehicle  to  aid  in 
carrying  zinc  chlorid  to  position  in  the  canal,  especially  of  an  upper  root. 
Asbestos  is  given  preference  to  cotton  by  some.  Tin  or  gold  foil  makes 
an  effective  root-canal  filling,  but  is  difficult  to  insert  without  leaving 
vacuoles.  Paraffin  combined  with  a  small  quantity  of  aristol  as  a 
material  to  fill  root-canals  has  been  suggested  by  Dr.  Kirk,  especially 
after  the  use  of  sodium  potassium.  This  agent,  being  a  most  active 
solvent  of  albuminous  matter,  in  a  measure  frees  the  ends  of  the  tubuli 
of  a  canal  of  their  organic  contents,  a  favorable  condition  for  the  use  of 
paraffin.  Paraffin  is  aseptic,  melts  at  a  low  temperature  and,  with  a 
heated  root-canal  drier  can  be  flowed  into  the  ends  of  the  tubuH  or 
into  a  minute  canal  not  considered  safe  to  open  up  extensively.  Re- 
cently, chloro-rosin  has  been  recommended  by  Dr.  Callahan  as  a  root- 
canal  filling  that  will  penetrate  the  exposed  ends  of  the  tubuH  in  the 
dentin  and  adhere  to  the  walls  of  the  canal. 

I^  Rosin  gr.  xi 
Chloroform  3  iii 

Ordinary  gutta-percha  should  be  used  to  close  a  foramen  when  an 
abscess  has  just  been  treated  by  injecting  through  it.  The  rubber- 
dam  is  placed  on  the  root  or  it  is  otherwise  protected  from  the  saliva, 
the  canal  washed  with  alcohol,  and  dried.  The  length  of  the  canal 
should  be  measured  with  a  hook-pointed  broach  and  gaged  with  a  small 
perforated  disk  of  rubber-dam  slipped  upon  the  instrument,  as  shown 
at  D,  Fig.  89.  The  gutta-percha  should  then  be  carried  to  position  on 
the  point  of  a  canal  plugger,  the  point  having  been  heated  just  enough 
to  cause  slight  adhesion  of  the  gutta-percha  F.  An  allowance  should 
be  made  for  the  displacement  of  the  instrument  by  the  cone  on  the  point 
by  comparing  the  length  with  the  broach,  E.  The  cone  is  then  de- 
tached from  the  point  and  left  in  position  in  the  apex  by  giving  the 

^  Cotton  may  be  sterilized  by  immersing  it  for  a  time  in  a  saturated  solution 
of  iodoform  in  ether,  and  then  drying.  It  should  be  kept  in  a  tightly-corked 
bottle.     The  odor  of  iodoform  in  the  operating-room  is  thus  avoided. 


86 


CROWN-,  BRIDGR-,  AND  PORCELAIN-WORK 


instrument  a  twist,  G.  As  oil  of  eucalyptus  is  a  solvent  of  gutta- 
percha, the  application  of  this  oil  to  the  surface  of  the  gutta-percha 
is  recommended  in  its  final  insertion  as  better  adhesion  to  the  walls 
of  the  canal  is  thus  obtained. 

To  properly  fill  and  close  an  enlarged  foramen,  an  accurately  fit- 
ted plug  of  gutta-percha  should  be  used.  This  can  be  obtained  by  rolling 
a  strip  of  pink  base-plate  gutta-percha  into  the  form  of  a  long  tapering 
cone,  as  shown  at  H,  Fig.  90,  with  a  slightly  heated  spatula  on  a  glass 


E  r 

i 
1 


H       I     J     K  L 


Pig. 


Fig.  90. 


slab  which  has  been  dipped  in  hot  water.  With  the  end  of  the  cone 
held  by  the  fingers,  the  point  is  inserted  up  the  canal  and  pressed  into 
the  foramen,  and  the  line  of  the  surface  of  the  end  of  the  root  marked 
on  the  cone,  which  is  then  withdrawn.  The  length  of  the  cone  in  the 
canal  is  compared  with  the  measure  of  the  canal,  as  shown  by  the  broach 
L  and  the  surplus  that  protrudes  through  the  foramen  is  cut  off.  The 
cone  is  again  inserted  up  the  canal,  marked,  then  removed  and  trimmed 
until  the  cone  fits  closely  in  the  apex  of  the  root,  as  illustrated  at  I.  It  is 
then  removed  and  about  one-fourth  of  an  inch  of  the  section  that  fits 
into  the  foramen  is  cut  off,  J.  The  cut-off  portion  is  next  mounted  on 
the  point  of  a  canal  plugger  which  has  been  heated  in  an  alcohol  flame 
just  enough  to  cause  adhesion  of  the  gutta-percha,  as  shown  at  K.  A 
little  of  the  point  of  the  cone  is  then  trimmed  off,  causing  the  remaining 
portion,  which  is  slightly  larger,  to  require  pressure  to  place  it  in 
position  in  the  foramen.  The  length  of  the  canal  is  then  gaged  on  the 
shank  of  the  plugger  from  the  point  of  the  cone  with  the  rubber-dam 
which  has  previously  been  placed  there,  as  shown  at  K  and  L.  The 
canal  is  next  washed  with  alcohol  and  dried.     The  cone,  having  been 


PULP  LESS  TEETH 


37 


dipped  in  oil  of  eucalyptus,  is  inserted  and  pressed  up  the  canal  until 
the  disk  on  the  plugger  meets  the  surface  of  the  end  of  the  root,  which 
indicates  that  the  cone  is  in  correct  position  in  the  foramen.  The 
plugger  is  then  twisted  around  several  times  to  disengage  it  from  the 


Fig.  91. 
Pig.  91. — Radiograph  of  a  fractured  central  incisor  of  a  boy  nine  years  old 
with  the  large  foramen  incident  to  his  age  closed  with  a  measured  gutta-percha 
cone  and  the  remainder  of  the  canal  as  yet  unfilled. 

gutta-percha.  Fig.  91  shows  a  case  treated  as  described.  If  the 
plugger  is  pressed  beyond  the  line  at  the  disk,  the  gutta-percha  will 
be  proportionately  protruded  through  and  beyond  the  foramen. 


Fig.  92. 


Fig.   93. — G,  Gutta-percha;  O,  oxychlorid; 
P,  post. 


When  two  canals  in  a  root  terminate  in  the  same  foramen,  it  is 
best  closed  by  first  filling  the  canal  through  which  the  foramen  is  most 
easily  reached  (Fig.  92)  after  which  the  other  canal  is  filled.  Ample 
room  should  be  left  in  any  root-canal  which  is  to  receive  the  post  of  a 
crown,  as  any  part  of  the  canal  not  occupied  by  the  post  will  later  be 
filled  with  the   cement. 


,88  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

When  a  post  has  been  fitted  to  a  canal  previous  to  the  closure  of  the 
foramen,  the  foramen  should  be  closed  with  gutta-percha,  the  oxy- 
chlorid  pumped  up  the  canal  and  the  post  inserted.  When  the  ce- 
ment is.  about  half  set,  the  post  is  seized  with  pliers  and  withdrawn 
and  not  again  inserted  until  the  cement  is  perfectly  set.  In  this  man- 
ner an  oxychlorid  socket  is  formed  into  which  the  post  will  fit  accurately 
(Fig.  93).  The  same  can  be  done  with  the  post  of  a  finished  crown,  if 
the  foramen  has  been  previously  closed  with  gutta-percha. 

A  pulpless  tooth  presented  for  crowning,  the  roots  of  which  have 
been  treated  and  filled  in  some  previous  operation,  should  be  carefully 


Fig.  94. 


examined.  If  the  slightest  doubt  is  entertained  as  to  its  hygienic 
condition,  it  should  receive  antiseptic  treatment  as  previously  de- 
scribed, as  the  ultimate  success  of  crown- work  depends  primarily  upon 
the  thoroughness  of  the  preliminary  operations.  Fig.  94  shows  radio- 
graphs of  properly  filled  root-canals,  which  are  the  superior  cuspid  and 
inferior  bicuspid  shown  unfilled  in  Fig.  84.  The  approved  method  in 
practice  is  to  take  preliminary  radiographs  to  determine  the  form  and 
condition  of  roots  and  canals  of  teeth  and  then  again  other  radiographs 
during  stages  of  the  treatment,  and  finally  to  determine  the  effective- 
ness of  the  operation. 


CHAPTER  IV 
CHRONIC  ALVEOLAR  ABSCESS 

THE  USUAL  FORMS — ABSCESS  OF  THE  FIRST  FORM — ABSCESS  OF  THE 
SECOND  FORM — EXOSTOSIS — THIRD  FORM,  BLIND  ABSCESS — ALVEO- 
LAROTOMY — GRANULOMA — APICOECTOMY,  AMPUTATION  OF  THE 
APEX  OF  A  ROOT — HYDROGEN  PEROXID — PROGNOSIS  OF  CHRONIC 
ALVEOLAR  ABSCESS  AND  APICOECTOMY — PERFORATION  OF  A  SIDE- 
WALL  OF  A  ROOT-CANAL  OR  OF  THE  DENTIN  AT  THE  BIFURCATION 
OF    THE    ROOTS 

Many  teeth  and  roots  presented  for  crown- work  are  affected  with 
chronic  alveolar  abscess.  A  general  description  of  an  effective  method 
of  treatment  is  therefore  properly  associated  with  a  discussion  of  the 
subject. 

The  cause  of  chronic  alveolar  abscess  will  be  found  in  a  continuation 
of  those  conditions  which  originally  produced  the  acute  form.  The 
tooth  or  roots  being  pulpless,  pyogenic  organisms  and  septic  gases, 
generated  by  the  decomposition  of  organic  matter  in  the  root-canal 
and  in  the  tubuli  of  the  dentin  find  an  outlet  through  the  foramen  into 
the  apical  space,  or  by  failure  of  root-canal  filling  present  to  effectually 
prevent  infection  from  the  oral  cavity,  causing  pericementitis  and  forma- 
tion of  pus.  The  general  treatment  consists  in  the  removal  of  all 
septic  matter  and  gases  from  the  root-canal  and  dentinal  tubuli,  the 
destruction  and  removal  of  the  pus-sac,  the  application  of  suitable 
therapeutic  agents  and  the  adoption  of  measures  to  prevent  further 
formation  of  pus. 

The  Usual  Forms. — Chronic  alveolar  abscess  is  usually  found  in 
the  following  forms :  First,  abscess  with  fistulous  opening  through  the 
alveolus  and  gum  and  accessible  through  the  root-canal  and  foramen. 
Second,  abscess  with  fistulous  opening  but  not  accessible  through  the 
apical  foramen.  Third,  abscess  without  a  fistula  and  from  which  pus 
discharges  through  the  apical  foramen  and  root-canal,  or  does  so  as 
soon  as  the  foramen  is  opened,  termed  blind  abscess. 

Abscess  of  the  First  Form. — In  the  treatment  of  an  abscess  of  the 
first  form,  the  canal  should  be  enlarged,  as  described  in  the  treatment  of 
pulpless  teeth,  and  the  foramen  opened  with  broaches  without  the  use 

89 


90 


CROWN-,  BRIDGE-,  AND  FORCEL  A  IN-WORK 


of  a  drill.  Aromatic  sulfuric  acid  on  cotton  placed  in  the  end  of  the 
canal  for  a  day  will  usually  open  up  the  most  minute  foramen,  A  small 
quantity  of  75  per  cent,  aqueous  solution  of  sulphuric  acid  pumped  into 
the  extremity  of  the  canal  will  often  enable  a  broach  to  instantly  effect 
a  passage.  The  saline  solution  slightly  colored  with  tincture  of  iodin 
is  then  forced  through  the  foramen  with  a  fine-pointed  syringe  (Fig.  95) 
introduced  well  up  the  canal  and  surrounded  with  a  packing  of  gutta- 
percha; or  it  may  be  pumped  up  with 
cotton  on  a  serrated  broach  until  it  passes 
into  the  abscess  and  out  through  the  fistula. 
This  is  followed  by  pumping  through  with 
a  broach  carbolic  acid  95  per  cent,  or  some 
other  preferred  agent.  Aromatic  sulfuric 
acid  may  also  be  injected  through  the 
foramen  or  the  fistulous  opening  into  the 
abscess  a  few  times  in  cases  that  do  not 
quickly  respond  to  other  treatment. 

Abscess  of  the  Second  Form.^ — When 
calcification  has  caused  the  obstruction 
in  the  canal,  enlarge  the  canal  as  far  as 
possible  with  broaches  and  Gates-Glidden 
drills.  Next,  guided  by  the  outline  of  the 
root  and  canal,  as  shown  by  a  radiograph, 
with  small-sized  burs  penetrate  the  cal- 
cified area.  When  the  latter  is  accomplished, 
with  a  small,  sharp-pointed  round  broach  and  sulfuric  acid  endeavor 
to  make  a  passage  to  and  directly  through  the  foramen  into  the 
abscess,  as  the  apical  section  of  the  canal  is  not  always  entirely 
calcified.  Placing  a  little  of  the  acid  in  the  extremity  of  the  root  to 
remain  for  two  or  three  days  will  sometimes  aid  the  operation.  Drilling 
directly  through  the  end  of  a  root  should  be  practiced  only  when 
other  treatment  fails,  as  the  opening  made  seldom  follows  the  line 
of  the  canal  through  the  foramen. 

Exostosis. — When  exostosis  closes  the  foramen,  the  root-canal 
should  be  sterilized  and  filled  and  the  affected  portion  of  the  end  of  the 
root  removed  (see  Apicoectomy)  and  the  area  of  the  sinus  curetted. 

Third  Form,  Blind  Abscess. — In  these  cases  first  open,  clean  and 
disinfect  the  canal  and  enlarge  the  foramen  with  broaches  and  root- 
canal  files,  if  necessary  aided  by  sulfuric  acid,  so  that  the  largest  size 
will  pass  freely  into  the  abscess.  Through  the  enlarged  foramen,  by 
aspirating  and  then  gently  injecting,  wash  out  the  abscess  cavity  at 
first  daily  with  the  saline  solution  or  absolute  alcohol  or  both,  using  a 


Pig.  95. 


CHRONIC  ALVEOLAR  ABSCESS 


91 


sub  Q  or  similar  syringe  with  ihe  smallest  size  gold  point,  gage  No. 
22,  or  pumping  with  cotton  on  a  broach.  In  some  cases  the  point  of  the 
syringe  may  be  introduced  through  the  foramen  directly  into  the  ab- 
scess cavity.  Another  syringe  of  the  same  style  may  be  used  to  with- 
draw the  injections  and  contents  of  the  abscess  cavity  by  inserting 
the  point  with  a  packing  up  the  root-canal  and  withdrawing  the  piston. 
In  this  way  the  injections  may  be  repeated  and  withdrawn.  The  canals 
are  next  filled  loosely  with  a  dressing  of  saturated  solution  of  aristol 
and  oil  of  cloves,  eucalyptus  or,  preferably,  oil  of  myrtol,  if  tooth  dis- 
coloration is  to  be  avoided.  Insert  a  small  probe  in  the  canal,  pack 
the  orifice  and  cavity  with  gutta-percha,  press  on  the  gutta-percha  and 
withdraw  the  probe.  The  aperture  left  by  the  probe  furnishes  a  small 
vent.  Continue  this  line  of  treatment  until  evidence  of  suppuration 
ceases,  then  temporarily  pack  the  canal  closely  with  the  medicated 
dressing  and  seal  the  cavity,  first  with  and  later  without  a  vent.  After 
the  lapse  of  three  or  more  weeks,  should  the  indications  appear  favor- 
able on  removal  of  the  dressing,  and  as  viewed  in  a  radiograph,  close 
the  foramen  with  a  cone  of  gutta-percha,  carefully  avoiding  pressure 
of  air  or  excessive  protrusion  of  the  gutta-percha  into  the  apical  space. 

If  the  abscess  is  only  acute  or  small  this  method,  if  skilfully  prac- 
ticed, will  usually  effect  a  cure.     Should  this  treatment  fail,  an  opening 
through  the  gum  and  alveolus  into  the 
abscess  must  be  obtained  (see  Alveolar- 
otomy)  and  the  same  course  pursued 
as  described  in  the  first  form  of  abscess. 

Alveolarotomy. — For  this  operation 
the  length  of  the  root  and  position  of 
the  apex  should  first  be  accurately 
determined.  This  is  best  done  by  the 
aid  of  a  radiograph  and  introducing  a 
broach  with  a  hook  point  through  the 
canal  and  foramen — if  it  is  open — into 
the  abscess  and  then  slowly  withdrawing 
the  broach.  In  the  withdrawal  the  hook 
by  catching  on  the  apex  indicates  both 
the  position  and  the  length  of  the  root 
(Fig.  96) .    A  small  pellet  of  gutta-percha 

or  a  little  disk  of  heavy  rubber-dam  placed  on  the  broach,  as  shown 
at  A,  will  form  an  accurate  gage.  After  the  withdrawal  of  the  broach  a 
straight  line  probe  is  passed  up  the  canal  through  the  foramen  into  the 
abscess  and  left  there  in  position.  The  exposed  portion  (A,  Fig.  97) 
will  fairly  indicate  the  direction  in  which  the  root  points,  and  should 


Pig.  96. 


92  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

there  be  no  considerable  curve  towards  the  apex,  the  line  in  which 
the  abscess  cavity  is  most  likely  to  be  found.  The  hook  broach  B 
is  then  placed  externally  with  its  shank  exactly  parallel  with  the  probe 
A  in  the  canal,  and. the  line  of  the  broach  and  more  especially  the 
location  of  the  hook  point,  marked  on  the  gum  with  carbolic  acid.  A 
few  shreds  of  cotton  twisted  around  the  broach,  especially  at  the 
point,  will  aid  in  carrying  and  holding  the  acid. 

In  the  manner  described,  aided  by  a  radiograph,  the  line  of  the  root 
and  the  position  of  the  apex  can  be  located  within  a  small  fraction  of  an 
inch,  and  as  well  the  cavity  of  the  abscess,  which  may  be  a  little  to  the 
right  or  left  of  the  apex.  The  membrane  at  the  spot  marked  is  then 
punctured  and  entrance  to  the  apex  of  the  root  and  apical  space  and 
abscess  effected  through  the  bone  with  a  small  spear-shaped  drill  and 
spoon-shaped  excavators.  The  fine  probe  protruding  through  the 
foramen  into  the  abscess  will  additionally  aid  the  operator  in  locating 
the  abscess  cavity  and  root  apex.  The  membrane  may  be  anesthet- 
ized, preferably  by  conductive  anesthesia,  previous  to  the  operation, 
or  the  operation  may  be  performed  under  analgesia.  Local  hypo- 
dermic injections  dilate  the  tissue,  which  is  an  interference  with  the 
operation. 

An  entrance  into  the  apical  space  can  be  made  almost  painlessly 
in  the  following  manner,  as  described  by  Dr.  G.  V.  Black:  "The  mucous 
membrane  is  first  dried  at  the  point  at  which  it  is  desired  to  make  the 
opening,  and  napkins  are  so  placed  as  to  keep  it  dry.  Then  a  plugging 
instrument  with  fairly  sharp  serrations  and  of  convenient  shape  is 
selected,  the  point  of  this  dipped  into  a  95  per  cent,  solution  of  carbolic 
acid,  and  a  drop  conveyed  to  the  mucous  membrane;  this  will  at  once 
produce  a  white  eschar.  Then  a  slight  scratching  motion  with  the 
serrated  point  is  begun,  with  the  view  of  removing  the  tissue  that  is 
whitened.  This  is  continued  until  the  carbolic  acid  is  thick  with  debris 
of  the  tissue  torn  up,  then  it  is  dried  out  and  another  drop  added,  as 
before,  and  the  process  continued.  This  is  repeated  as  often  as  may  be 
necessary,  going  deeper  and  deeper  into  the  tissue  in  the  desired  direc- 
tion until  the  bone  is  laid  bare.  Then  a  fresh  drop  of  the  acid  is  placed 
on  the  bone,  and  the  periosteum  carefully  raised  over  a  sufficient  space; 
then  with  a  sharp  chisel  or  a  coarse  bur  cut  through  to  the  peridental 
membrane.  This  will  generally  cause  some  pain  and  some  hemorrhage, 
but  after  giving  a  little  time  for  this  to  cease  and  adding  more  of  the 
acid,  the  apical  space  can  usually  be  reached  without  difficulty.  No 
blood  should  be  drawn  at  any  time  during  the  operation  except  in 
penetrating  the  walls  of  the  alveolus.  In  doing  this  no  tissue  is  re- 
moved until  it  is  anesthetized  by  the  carbolic  acid.     This  is  a  little 


CHRONIC  ALVEOLAR  ABSCESS  93 

tedious,  but  is  almost  painless,  and  the  general  affect  is  usually  better 
than  by  other  modes  of  penetrating  the  apical  space.  The  carbolic 
acid  has  the  effect  of  modifying  the  pain,  and  the  opening  left  does  not 
close  so  readily. ' ' 

A  variation  of  this  method  is:  after  reaching  the  alveolus,  instead 
of  using  more  carbolic  acid,  press  pellets  of  adrenalin  and  cocain  into 
the  tissue.  In  this  manner  anesthesia  is  produced,  sufl&cient  for  the 
operation,  without  dilatation  of  the  tissues  by  injecting. 

In  these  cases,  curetting  of  the  cavity  of  the  abscess  and  apex  of  the 
root  is  most  effective,  but  removal  of  healthy  bone  tissue  should  be 
avoided  as  much  as  possible,  as  the  stability  of  the  root  and  sometimes 
of  the  adjoining  teeth  is  proportionately  impaired  thereby. 

A  period  of  entire  cessation  of  discharge  of  pus  is  to  be  considered 
the  most  favorable  indication  of  successful  treatment  of  alveolar 
abscess. 

Thorough  disinfection  and  sterilization  of  the  root-canals  and  dentin 
are  included  in  the  treatment  of  alveolar  abscess.  This  is  best  ac- 
complished by  saturating  the  dentin  with  a  solution  of  oil  of  cloves  and 
aristol  until  the  dentin  darkens  in  shade.  As  soon  as  the  treatment  is 
followed  by  favorable  indications,  the  foramen  should  be  closed  with 
gutta-percha  while  the  fistula  is  yet  open,  and  the  remainder  of  the 
canal  filled  with  zinc  oxychlorid  as  described  in  Chaper  III.  Any  fur- 
ther treatment  considered  necessary  can  be  conducted  externally 
through  the  fistula.  This  may  be  facilitated  by  enlarging  the  orifice 
with  tents  of  iodoform  gauze  and  in  very  small  places  with  iodoformized 
cotton  or  in  cases  of  small  abscesses  cotton  saturated  with  oil  of  cloves 
and  aristol.  Enlargement  of  the  fistula  tends  to  encourage  the  process 
of  granulation  in  the  region  that  has  been  occupied  by  the  abscess, 
especially  when  a  carious  or  necrosed  condition  of  the  bone  required  its 
removal. 

Aromatic  sulfuric  acid  is  a  powerful  astringent  and  germicide.  It 
will  be  found  most  useful  in  cases  where  only  a  very  slight  carious 
state  of  the  walls  of  the  alveolus  exists  and  does  not  indicate  the  necessity 
of  curetting.  Its  use,  however,  should  be  limited  and  in  subsequent 
external  treatment  through  the  fistula  some  of  the  other  therapeutic 
agents  may  be  employed,  such  as  the  essential  oils  or  carbolic  acid 
alone  or  combined  with  one  of  the  preparations  of  iodin. 

Injections  of  sulfuric  acid  in  the  region  of  the  mental  foramen  should 
be  made  cautiously  and  should  not  be  applied  to  an  abscess  bordering 
on  the  antrum  until  the  operator  is  positively  assured  that  the  abscess 
does  not  open  into  that  cavity. 


94  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Granuloma. — Granuloma  is  a  tumorous  growth  around  the  apex  or 
on  the  side  of  the  root  of  a  tooth.  It  is  caused  by  inflammation  and 
gradual  hypertrophy  of  the  pericementum,  pus  usually  not  being 
present.  The  treatment  is  removal  of  the  tumor,  curetting  of  the 
cavity  in  the  alveolus  and  if  indicated  amputation  of  the  affected  por- 
tion of  the  apex  of  the  root. 

Apicoectomy,  Amputation  of  the  Apex  of  a  Root.— In  chronic  al- 
veolar abscess  the  pus  cavity  occasionally  involves  the  alveolus  in  such 
a  way  as  to  destroy  a  considerable  portion  of  the  pericementum  of  the 
end  of  the  root.  The  cementum  of  that  part  is  consequently  devitalized 
and  the  portion  of  the  root  affected  becomes  degenerated  in  structure 
and  permeated  with  septic  matter.  In  this  condition  it  acquires  the 
character  of  a  foreign  substance,  proves  a  constant  source  of  irritation 
and  defies  all  efforts  of  the  membrane  to  perfectly 
inclose  or  encyst  it. 
y     ^-N  In  such  cases  when  curetting  of  the  abscess  cavity 

and  end  of  the  root  has  failed,  amputation  of  the  por- 
tion of  the  root  which  is  denuded  of  pericementum  is 
the  best  course  to  pursue.  This  also  is  the  only 
treatment  that  can  be  resorted  to  in  exostosis.  An 
incision  is  made  in  the  alveolar  tissues  sufficient  to 
fully  expose  the  affected  part  at  least  3^^  to  3''^  inch 
in  length.  Any  carious  or  necrosed  bone  in  the 
territory  is  then  curetted  and  the  end  of  the  root  re- 
PiG.  98.  moved   to  the  line  of  the  curetted  bone    (Fig.   98). 

The  root-canal  should  be  filled  solidly  with  gutta- 
percha previous  to  the  amputation  so  that  when  the  end  of  the  root 
is  excised  the  stump  will  be  left  smooth  and  snugly  filled. 

The  end  of  the  root  is  best  removed  by  first  locating  the  apex  and 
then  trimming  off  the  required  amount  with  a  fissure  or  rose-shaped 
bur.  The  instrument  should  be  held  at  a  right-angle  to  the  line  of  the 
root  in  an  apical  direction  to  avoid  a  slanting  amputation.  The  ground- 
off  particles  of  the  root  are  to  be  removed  by  injections  of  the  saline 
solution  into  the  cavity  during  and  after  the  operation. 

Gradual  removal  of  the  apex  as  described  is  preferable  to  cutting 
across  the  root  with  a  bur,  as  the  amputated  part  or  parts  are  occasion- 
ally difficult  to  remove.  When  the  required  amount  has  been  removed 
the  ledge  of  the  surface  of  <he  end  should  be  slightly  rounded  and 
the  surface  smoothed  with  fine  carborundum  and  gem  points. 

The  orifice  of  the  cavity  in  the  gum  should  be  kept  open  with  iodo- 
form gauze  and  douched  daily  for  two  or  three  days,  then  at  intervals 
of  three  or  four  days,  until  the  cavity  is  filled  by  granulation.     In  this 


CHRONIC  ALVEOLAR  ABSCESS  95 

method  of  treatment  any  imperfection  in  the  operation  will  be  evi- 
denced by  failure  of  the  part  to  properly  granulate  and  it  can  be  cor- 
rected. When  the  sinus  is  not  packed  and  external  tissue  is  drawn 
over  it  with  sutures  or  it  is  allowed  to  close  itself,  filling  of  the  sinus 
with  tissue  is  not  as  well  assured.  When  the  healing  process  is  com- 
pleted, crown-work  may  be  proceeded  with. 

Apicoectomy  is  much  simplified  and  often  more  effectively  per- 
formed in  cases  where  the  apex  is  deeply  seated  by  first  disinfecting 
the  root-canal,  curetting  the  abscess  cavity,  irrigating  through  the 
canal  and  fistula  fqr  one  to  three  days,  and  pressing  back  the  soft 
tissue  with  iodoform  gauze  to  expose  the  portion  of  the  root  to  be 
operated  on. 

The  amputation  of  the  apices  of  roots  requires  skill  and  experience 
and  had  better  be  confined  to  the  anterior  teeth  or  those  with  a  single 
root,  except  in  the  hands  of  experts.  The  preparatory  treatment 
described  simplifies  the  operation;  as  generally  practiced  the  hemor- 
rhage obstructs  the  view  of  the  parts  and  renders  liable  the  removal  of 
an  unnecessary  amount  of  tissue,  besides  increasing  the  severity  of  the 
operation  for  the  patient. 

Hydrogen  Peroxid. — Hydrogen  peroxid  should  not  be  used  in  the 
treatment  of  alveolar  abscess  except  where  there  is  a  large  vent  for  its 
free  expansion,  and  even  then  its  use  is  viewed  by  many  with  disfavor, 
as  it  destroys  granulation.  In  inclosed  or  partly  inclosed  areas,  it  is 
liable  to  extend  existing  infection.  In  cases  having  a  large  vent, 
immediately  subsequent  to  the  use  of  aromatic  sulfuric  acid,  hydrogen 
peroxid  may  be  used,  as  then  its  expansion  will  be  slight. 

Prognosis  of  Chronic  Alveolar  Abscess  and  Apicoectomy. — Roots 
affected  with  chronic  alveolar  abscess,  the  pus-sac  of  which  is  in  the 
line  of  the  apex  of  the  root  and  involves  only  a  small  portion  of  the 
alveolus,  can  be  considered  as  suitable  for  treatment  and  crowning 
operations.  When  the  area  of  pus  has  extensively  destroyed  the 
pericementum  at  the  apex  and  also  on  one  or  both  sides  of  the  root,  pro- 
portionately to  the  loss  of  the  pericementum  is  the  root  to  be  judged  as 
impaired.  In  alveolar"  abscess  and  exostosis  the  removal  of  one-fourth 
of  the  length  of  the  root  is  as  much  as  shows  a  proportion  of  success 
that  justifies  the  operation.  In  cases  of  very  long  roots,  the  removal  of 
one-third  may  be  favorably  considered.  A,  Fig.  99,  is  a  radiograph  of 
a  case  before,  and  B,  just  after  an  operation.  C  and  D  are  respectively 
two  and  five  months  later. 

An  amputated  root  should  not  be  used  as  a  support  in  bridge-work, 
although  it  may  be  included  in  a  bridge  supported  by  adjoining 
abutments. 


96 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Perforation  of  a  Side-Wall  of  a  Root-Canal  or  of  the  Dentin  at  the 
Bifurcation  of  the  Roots. — Extensive  perforation  by  decay  through  the 
side-walls  of  the  root-canal  of  a  tooth  considerably  below  the  line  of  the 
edge  of  the  alveolar  process  seldom  permits  of  successful  treatment. 
After  removal  of  the  decay,  if  only  a  very  slight  perforation  exists  or  if 
the  perforation  has  been  made  by  the  improper  or  careless  use  of  a  bur, 
cicatricial  tissue  may  be  induced  to  form  over  the  part  by  creating  and 
maintaining  a  sterilized  condition  and  then  sealing  the  aperture. 


Fig.  99. 

The  method  of  procedure  is  as  follows:  First  effect  sterilization  of 
the  dentin  and  canals  and  fill  the  canal  beyond  the  perforation.  Next 
apply  adrenalin  and  cocain  to  stop  all  hemorrhage  and  when  the  hem- 
orrhage has  ceased,  wash  and  syringe  the  canal  with  absolute  alcohol. 
Dry  the  canal  thoroughly  and  fit  closely  over  the  perforation  a  small 
flat  piece  of  gutta-percha,  or  gutta-percha  cement,  warmed  and  applied 
with  a  gentle  pressure,  sufficient  only  to  produce  adhesion  without 
forcing  the  gutta-percha  through.  The  filling  of  the  canal  can  then  be 
carefully  completed,  using  zinc  oxyphosphate.  If  this  method  proves 
unsuccessful  and  inflammation  ensues,  the  position  of  the  perforation, 


CHRONIC  ALVEOLAR  ABSCESS 


97 


aided  by  a  radiograph,  should  be  carefully  calculated  and  an  artificial 
fistula  formed  on  a  direct  line  with  it  through  the  gum  and  alveolar 
process,  Fig.  loo.  Carbolic  acid  may  be  used  to  obtund  the  tissue  in 
forming  the  fistula  as  already  described,  or  a  novocaine  injection 
administered.  The  necessary  perforation  through  the  alveolar  process 
should  be  small  in  diameter  and  be  made  with  a  drill.  Frequently  the 
position  for  the  intended  fistula  is  best  located  by  introducing  a  sharp- 


FlG.    100. 


Fig.  igi. 


pointed  curved  probe  into  the  canal  and  perforating  externally  through 
the  tissues.  Injections  can  then  be  made  outward  through  the  fistula 
and  the  perforation  sealed  with  gutta-percha,  similar  to  the  closing  of 
the  foramen  in  cases  of  alveolar  abscess. 

The  incisors  and  cuspids  are  frequently  perforated  through  the  side  of 
the  root-canal  by  the  unskiKul  use  of  drills  or  burs.  In  such  cases  the 
perforation  is  generally  caused  by  holding  the  hand-piece  of  the  dental 
engine  out  of  the  line  of  the  axis  of  the  tooth,  as  described  in  Part  III, 
Chapter  II,  and  shown  in  Fig.  loi. 

The  result  of  the  treatment  of  a  perforation  should  be  well  deter- 
mined before  proceeding  with  an  operation  on  the  root  or  tooth. 


PART  III 


CHAPTER  I 
ARTIFICIAL  CROWN-WORK 


FIRST  AUTHENTIC  ACCOUNT  OF  ARTIFICIAL  CROWNS  OR  PIVOT  TEETH — 
THE  FIRST  PORCELAIN  PIVOT  TEETH — GOLD  PIVOT  TEETH — FIRST 
PORCELAIN  AND  GOLD  PIVOT  TOOTH  OR  CROWN — THE  RICHMOND 
PORCELAIN  AND  GOLD  COLLAR  CROWN — THE  EARLIER  OPERATIONS — 
THE  MORRISON  AND  BEERS  GOLD  CROWNS — THE  FOSTER  AND  LAW- 
RENCE CROWNS — THE  MACK  AND  HOWLAND-PERRY  CROWNS — 
THE  GATES-BONWILL  CROWN — THE  HOW  CROWN — THE  WESTON 
CROWN — THE  BROWN  CROWN — »THE  NEW  RICHMOND  PORCELAIN 
CROWN — THE  LOGAN  CROWN — ADVANTAGES  CONFERRED  BY  IM- 
PROVEMENTS IN  CEMENTS — CLASSIFICATION  OF  MODERN  CROWN- 
WORK 

First  Authentic  Account  of  Artificial  Crowns  or  Pivot  Teeth. — The 

first  authentic  account  we  have  of  the  use  of  artificial  crowns  or  pivot 
teeth  is  given  by  Fau chard,  in  his  work  entitled  "Le  Chirurgien  Den- 
tiste  ou  Traites  des  Dents,"  in  1728.     Fig.  102  illustrates  the  crown  he 

C 


Fig.   102. — Fauchard's  "dent  a  tenon." 

describes.  The  root  was  filed  level  with  the  surface  of  the  gum,  the 
root-canal  enlarged,  cleaned  and  filled  with  lead,  A  hole  was  drilled 
in  the  lead  and  the  rough-surfaced  post  was  forced  into  the  soft  metal 
to  secure  it.  The  other  end  of  the  post  was  fastened  in  the  crown, 
which  was  either  a  natural  crown  or  one  made  of  ivory. 

De  Chemant  describes  the  use  of  porcelain  for  the  construction  of 
pivot  teeth  in  the  early  part  of  the  last  century.  From  that  time  on 
porcelain  has  been  used  and  has  gradually,  for  the  most  part,  super- 
seded other  materials  for  the  construction  of  crowns. 


I02  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

The  First  Porcelain  Pivot  Teeth. — The  porcelain  pivot  tooth  or 
crown,  Fig.  103,  was  the  form  used  for  many  years.  When  first  in- 
troduced it  was  attached  to  the  root  by  means  of  a  hickory-wood  pin 
or  pivot,  one  end  of  which  fitted  the  hole  in  the  center  of  the  crown  and 
the  other  that  of  the  root-canal.  The  moisture  of  the  mouth  by  swell- 
ing the  wood  fastened  the  pivot  in  both  tooth  and  root. 

It  was  found  that  the  wooden  pivot  in  time  caused  decay  of  the 
root,  was  liable  to  fracture  it  by  expansion,  and  it  also  affected  the 
breath.  These  objections  led  to  the  introduction  of  the  use  of  the  gold 
pivot. 

Gold  Pivot  Teeth. — Gold  pivots  in  the  early  days  of  their  use,  were 
variously  secured  to  root  and  crown.  In  the  crown  the  pivot  was 
fastened  by  incasing  it  with  wood  or  by  skilfully  flowing  a  little  gold 
sold-er  around  that  part  of  it  which  set  in  the  porcelain,  and  to  the  root 
by  fitting  in  the  canal  a  piece  of  hickory  and  inserting  the  pivot  in  the 
wood  or  by  twisting  fibers  of  cotton  or  silk  around  the  post  and  pressing 
the  crown  to  position. 


Pivot  Tooth  Root    Prepared 

FOR  Pivot 

Fig.  103,  Fig.  104. 

First  Porcelain  and  Gold  Tooth  or  Crown. — The  porcelain  pivot 
tooth  mounted  by  these  methods  was  superseded  by  the  use  of  a  plain- 
plate  porcelain  tooth  backed  with  gold  and  soldered  to  a  piece  of  plate 
stamped  out  to  accurately  fit  the  end  of  the  root  and  soldered  to  the 
pivot  or  pin,  as  shown  in  Fig.  104.  A  later  improvement  in  the  at- 
tachment of  the  crown  consisted  in  tightly  fitting  the  pivot  into  a  gold 
tube  screwed  into  the  root.  This  latter  method  was  devised  to  avoid 
the  objectionable  features  connected  with  the  use  of  wood.  The  transi- 
tion from  this  last  mentioned  method  to  those  of  modern  crown-work, 
though  most  important  in  their  results,  is  not  so  marked  as  regards 
constructive  details. 

The  Richmond  Porcelain  and  Gold  Collar  Crown.— The  gold  collar 
crown  with  porcelain  facing  of  present  use  is  practically  the  gold  backed 
pivot  tooth  of  former  years  with  the  addition  of  a  collar;  though  ap- 
parently simple  to  conceive,  it  was  slow  of  development.  It  was  not 
until  such  a  form  was  presented  and  its  advantages  demonstrated  by 
Dr.  C.  M.  Richmond,  about  1876,  that  its  true  value  and  possibiHties 


ARTIFICIAL  CROWN-WORK 


103 


were  appreciated,  more  especially  respecting  the  support  it  was  capable 
of  affording  in  bridge-work  operations. 

The  Earlier  Operations. — The  earlier  operations  in  porcelain  crown- 
work  were  almost  entirely  confined  to  the  incisor  and  cuspid  teeth,  the 
object  being  restoration  for  appearance  rather  than  utility.  We  find, 
however,  on  investigating  the  history  of  the  art,  that  some  effort  was 
also  made  by  a  few  of  the  earlier  practitioners  to  maintain  and  restore 
the  usefulness  of  affected  posterior  teeth  with  crown-work.  Prominent 
among  these  was  J.  Paterson  Clark,  a  dental  practitioner  in  London, 
who,  as  early  as  1836  published  a  description  of  his  method  of  restoring 
decayed  and  abraded  molars  to  usefulness  by  covering  them  with  gold 
caps  stamped  up  on  a  metal  die  of  the  tooth. 

The  Morrison  and  Beers  Gold  Crowns. — Similar  operations  were 
described  and  practiced  later  on  in  this  country  by  Dr.  Wm.  H.  Dwin- 
elle,'  who  in  1855  related  the  method  for  the  application  of  a  crown  with 
a  porcelain  facing,  and  Dr.  W.  N.  Morrison, ^  in  1869,  and  were  brought 


Fig.  105. 


into  more  prominence  by  Dr.  J.  B.  Beers,^  who  in  1873  secured  a  patent 
for  his  method  of  capping  teeth  with  gold,  as  illustrated  in  Fig.  105. 

During  the  progressive  modifications  in  crown- work  which  evolved 
from  the  gold  pivot  tooth  or  crown  to  the  gold  collar  porcelain  crown 
of  the  present  time,  many  improvements  on  the  original  porcelain 
pivot  tooth  as  a  ready-made  crown  were  developed  and  introduced  into 
practice.  One  of  the  first  of  this  character  to  attain  prominence  was 
the  Foster  Crown. 

The  Foster  and  Lawrence  Crowns. — The  Foster  crown  introduced 
by  Dr.  E.  W.  Foster,  in  1855  and  so  named,  although  similar  'o  one 
patented  by  Dr.  H.  Lawrence,  in  1849,  differed  from  the  commonly  used 
pivot  tooth  in  having  a  perforation  in  the  center  of  the  palatal  side  on 

^  American  Journal  of  Denial  Science,  April,  1855. 
2  Missouri  Denial  Journal,  May,  1869. 
^  Circular  lo  the  Dental  Profession,  1873. 


I04 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


a  line  with  the  root-canal.  The  orifice  was  shaped  to  accommodate  the 
head  of  a  screw  (Figs.  io6  and  107)  by  which  the  crown  was  attached 
to  the  root.  The  object  of  this  form  was  to  dispense  with  the  use  of 
wood  as  a  pivot  or  post. 


Pig.  106. 


Fig.  107. 


Pig.  108. 


Pig.  109. 


The  Mack  and  Howland-Perry  Crowns. — The  first  form  of  porcelain 
crown  introduced  which  protected  the  end  of  the  root  by  the  use  of 
cement  for  its  attachment  was  devised  by  Dr.  C.  H.  Mack,  in  1872. 
It  consisted  of  a  hollow  porcelain  crown  with  a  cavity  in  the  base  of  a 
shape  and  size  to  admit  the  extremities  of  pins  screwed  into  the  root  or 
cemented  in  the  canal.  The  crown  was  cemented  on  the  root  over 
these  pins  with  gutta-percha,  amalgam  or  zinc  oxychlorid.  The 
Mack  crown  proved  unreliable  in  practical  use  because  of  the  insecurity 
of  the  attachment.  The  Howland  and  Perry  crowns,  which  were  so 
nearly  identical  that  they  became  known  as  the  Howland-Perry  crown 
(Figs.  108  and  109),  improved  on  the  Mack  by  imparting  to  the  cavity 
in  the  base  a  better  form  for  the  retention  of  the  screws  in  the  cement 
and  a  more  suitable  curve  to  the  base. 


Fig.  no. 


Pig.  III. 


The  Gates-Bonwill  Crown.— The  next  notable  improvement  in 
all-porcelain  crowns  appeared  in  the  Gates  and  Bonwill  crowns,  the 
former  being  the  invention  of  Dr.  W.  H.  Gates,  about  1875,  and  the 


A  R  TIF  I  CI  A  L  CRO  WN-WORK 


105 


latter  of  Dr.  W.  G.  A.  Bonwill,  in  1881.  These  also  were  so  nearly 
alike  that  they  were  called  Gates-Bonwill  (Figs,  no  and  in).  One  of 
the  advantages  this  crown  possessed  over  the  Foster  was  that  amalgam 
was  used  for  its  attachment,  thus  protecting  the  end  of  the  root  from 
decay.  The  base  of  the  crown  was  concave  and  the  aperture  for  the 
post  of  a  triangular  form.  The  crown  was  secured  to  the  root  with  a 
screw  post,  or  a  flat  pin  with  tapering  ends,  anchored  with  the  amalgam 
that  attached  the  crown.  This  crown  was  extensively  used  for  several 
years. 


Pig.  112. 

The  How  Crown. — The  How  crown  (Fig.  112)  was  invented  by  Dr. 
W.  S.  How,  in  1883.  Its  novel  feature  was  the  formation  of  a  suffi- 
cient concavity  in  the  palatal  side  of  the  incisors  and  cuspids  to  afford 
space  for  four  pins  in  the  porcelain,  with  room  between  them  for  the 
adjustment  of  the  screw  post.  The  crown  when  fitted  was  attached 
by  bending  the  pins  around  the  post  and  packing  around  them  and 
filling  the  cavity  of  the  crown  with  amalgam. 

The  Weston  Crown. — The  Weston  Crown,  introduced  by  Dr. 
Henry  Weston  about  the  same  time,  was  similar  in  principle  and  struc- 
ture, with  this  difference:  The  Weston  post  was  flat  and  riveted  to  the 
crown  before  insertion.     The  post  was  first  cemented  in  position  with  a 


Fig.  113. 

small  quantity  of  zinc  oxyphosphate  and  the  remainder  of  the  space 
then  filled  with  either  gold  or  amalgam.  Fig.  113  shows  the  various 
steps  in  the  operation. 

The  Brown  Crown. — Another  form  of  modern  introduction  but 
limited  use  was  the  Brown  crown,  illustrated  in  Fig.  114.  It  was 
made  with  a  conical  base  and  with  a  long  post  baked  in  the  porcelain. 


io6 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


In  mounting  it  the  end  of  the  root  was  concaved  to  receive  the  convex 
porcelain  base.  The  object  of  this  form  of  construction  was  to  permit 
the  porcelain  to  be  removed  in  a  close  "bite"  without  materially  weak- 
ening the  crown. 

The  New  Richmond  Porcelain  Crown. — In  the  New  Richmond 
porcelain  crown,  illustrated  in  Fig.  115,  which  was  also  of  the  11- 
porcelain  variety,  a  V-shaped  cavity  was  provided  at  the  base  to  exert 


Fig.  114. 

some  degree  of  lateral  pressure  on  the  root  and  thus  help  to  guard 
against  its  fracture. 

The  Logan  Crown. — The  Logan  crown,  formerly  so  extensively 
used,  was  invented  by  Dr.  M.  L.  Logan.  Its  distinctive  features  are 
the  cupping  out  of  the  base  surrounding  the  strong  platinum  post, 
the  form  of  the  post,  and  the  baking  of  the  post  in  the  porcelain.  As 
originally  made  the  post  was  round,  but  shortly  after  the  tapered  I- 
beam  post  was  introduced.     Fig.  116  shows  the  Logan  Crown  in  section. 

The  development  of  what  were 
classed  as  ready-made  porcelain 
crowns  as  here  traced,  brings  us  to 
the  forms  which  are  now  in  use  and 
which  will  be  described  in  the  suc- 
ceeding chapter. 


Fig.  115. 


Fig.   116. 


Advantages  Conferred  by  Improvements  in  Cements. — Doubtless 
much  of  the  present  perfection  of  methods  by  which  the  effective 
results  now  achieved  in  this  branch  of  dental  prosthesis  are  made 
possible,  is  due  to  the  use  of  cements  with  which  the  ends  of  roots  and 
crowns  are  hermetically  inclosed.  Of  these  the  first  was  zinc  oxy- 
chlorid,  introduced  about  i860,  though  not  used  in  this  work  till  some 


A  R TIFICTA  L  CROWN-WORK 


107 


years  later.  More  important  was  zinc  oxyphosphate,  first  made  known 
about  1877,  while  a  better  understanding  of  the  properties  of  gutta- 
percha as  applied  to  this  purpose  has  contributed  not  a  little  to  the 
results. 

Classification  of  Modern  Crown-Work. — Modern  artificial  crown- 
work  affords  extensive  facilities  for  restoring  the        arc 
crowns  of  natural  teeth  and  furnishes  means  of 
support  for  bridge-work. 

In  the  consideration  of  modern  crown-work 
presented  in  the  succeeding  chapters  the  subject 
is  divided  into  two  general  systems. 

Under  the  First  System  of  crown-work  as 
shown  in  Fig.  117,  will  be  included  all  porcelain 
post  crowns  in  which  the  post  is  first  firmly 
anchored  in  the  pulp-canal  and  the  crown  then 
cemented  on  the  projecting  end  of  the  post 
termed:  all-porcelain  detached-post  crown  (A);  all-porcelain  detached- 
post  crown  on  a  metallic  base  (B);  and  porcelain-faced  metallic  post 
crowns  (C). 

The  Second  System  will  include  such  methods  in  crown-work  as 
are  illustrated  in  Fig.  118,  in  which  collars,  bands  or  ferrules  as  vari- 
ously designated,  are  used  to  encircle  the  cervix  in  crowning  operations 


Fig.   117. 


m 


Pig.   118. 


namely:  all-metallic  collar  crown  (A) ;  collar  crown  with  porcelain 
facing  (B);  detached-post  crown  on  capped  root  (C);  porcelain  jacket 
crown  (D)  and  various  styles  of  combined  metal  and  porcelain  crowns. 
Following  the  descriptive  details  of  these  two  systems  partial 
crown  or  inlay-work  and  special  operations  in  crown-work  will  be 
described. 


CHAPTER  II 

PRINCIPLES  ENTVOLVED  IN  CROWN -WORK 

NOMENCLATURE  OP  CROWN-WORK — THE  OBJECT  OF  CROWNING  OPERA- 
TIONS— THE  SUBJECT  OF  OCCLUSION — MALFORMED  OCCLUSAL  SUR- 
FACES— MEDIAN  LINE  OF  NATURAL  CROWN  AND  ROOT — THE  POST 
IN  RELATION  TO  CANALS  AND  ROOTS — THE  POST  IN  RELATION  TO 
POST  OR  DOWEL  CROWNS — SHORT  AND  LONG  CROWNS — PRINCIPLES 
GOVERNING  THE  CONSTRUCTION  OF  ROOT-CAPS  WITHOUT  COLLARS — 
POSTS  IN  RELATION  TO  CROWNS — SELECTION  OF  PORCELAIN  TEETH 
— ^DEPENDENCE    OF    CROWN-WORK    OPERATIONS    ON    ASEPSIS 

Nomenclature  of  Crown-Work. — To  systematize  and  explain  the 
nomenclature  used  in  the  descriptive  details  of  crown-work,  the 
following  definitions  of  terms  used  are  given  (See  Fig.  119): 

1.  Apex.  19.  Plate,  coping,  or  cap.     (This  part 

2.  Cervix.  when  a  collar  is  used  is  termed  the 

3.  Cervico-lingual  surface.  floor.} 

4.  Cervico-labial  surface.  20.  Slot  between  cap  and  base  of  porce- 

5.  Labial  surface.  lain  facing. 

6.  Lingual  surface.  21.  Back  of  porcelain  facing. 

7.  Incisal  end.  22.  Metallic  backing. 

8.  Occlusal,     occluding,  or    grinding       23.  Metallic  backing  on  incisal  surface. 

surface.  Incisal  backing. 

9.  Lingual  cusp.  24.  Post,  dowel,  pin,  or  pivot. 

10.  Buccal  cusp.  25.  Base  of  crown. 

11.  Sulcus.  26.  Collar,  band  or  ferrule. 

12.  Root-canal.  27.  Cervical  edge  of  collar  or  crown. 

13.  Surface  of  end  of  root.  28.  Occlusal  edge  of  collar. 

14.  Labial  or  buccal  section  of  end.  29.  Occlusal  cusps  or  grinding  surface. 

15.  Lingual  section  of  end.  30.  Occlusal  third  of  a  tooth. 

16.  Post,  dowel,  pin,  or  pivot.  31.  Middle  third  of  a  tooth. 

17.  Point  of  post.  32.  Cervical  third  of  a  tooth. 

18.  End  of  post. 

Mesial  side,  towards  the  median  line  of  the  mouth. 

Distal  side,  from  the  median  line  of  the  mouth. 

Cavo-surface,  the  cavity  or  inside  surface  of  a  cap,  crown  or  inlay. 

Dummy,  an  artificial  bridge  tooth  between  abutments. 

MOD  crown,  a  crown  covering  only  the  mesial,  occlusal  and  distal  surfaces. 

M  O  D  L  crown,  a  crown  covering  the  mesial,  occlusal,  distal  and  lingual  sur- 
faces but  not  the  labial  or  buccal. 

Lug,  a  projection  of  metal  that  either  rests  on  a  tooth,  artificial  crown  or  inlay, 
or  fits  into  a  socket  formed  in  them.     Also  termed  a  spur  or  flange. 

108 


PRINCIPLES  INVOLVED  IN  CROWN-WORK 


log 


In  whatever  form  teeth  and  roots  are  presented  for  crown-work, 
invariable  scientific  and  mechanical  principles  govern  the  application, 
although  the  style  or  method  of  construction  admits  of  selection.  The 
general  condition  of  the  roots  or  teeth  to  be  operated  upon  and  the 
character,  direction,  and  force  of  the  occlusion  are  subjects  that  gov- 
ern the  application.  The  location  in  the  mouth  and  the  object  of  the 
operation  indicate  the  preferable  style  or  method  of  construction. 
Operations  on  the  eight  anterior  teeth  will  generally  be  influenced  by 
appearance  and  those  on  the  posterior  teeth  principally  by  utility. 


21 


Fig.  119. 

The  Object  of  Crowning  Operations.— Crown- work  ordinarily  is 
classed  in  tooth  conservation  as  a  resort  subsequent  to  the  failure  of 
filling.  In  the  crowning  of  roots  and  pulpless  teeth  having  the  coronal 
section  practically  destroyed  by  decay,  protection  against  its  recurrence, 
fracture  of  the  root  and  restoration  of  normal  contour  are  the  subjects 
to  be  especially  considered.  In  cases  where  sound  teeth,  or  teeth 
with  or  without  living  pulps,  only  sHghtly  decayed,  are  to  be  capped 
with  gold  as  supports  for  bridges,  the  work  is  to  be  conducted  princi- 
pally with  a  view  to  the  preservation  of  the  coronal  sections  as  well  as 
their  utilization  as  abutments. 


no  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Requirements  in  Crown-Work 

Physiological  Relations. — Preliminary  to  a  crowning  operation  a 
careful  examination  should  be  made  of  the  investing  and  surrounding 
membrane.  Any  existing  pathological  condition  should  be  carefully 
examined  and  the  parts  radiographed.  Should  a  pathological  condi- 
tion exist  the  diagnosis  of  which  as  well  as  the  prognosis  is  favorable, 
treatment  should  be  applied  and  a  favorable  result  assured  before 
crown- work  is  commenced. 

Anatomical  Relations. — Anatomical  reproduction  of  the  normal 
tooth  form  on  all  the  surfaces  as  far  as  the  conditions  in  the  case  will 
permit,  is  a  necessity  in  modern  crown-  and  bridge-work,  as  normal 
tooth  form  is  the  basis  of  physical  benefit  to  be  derived,  as  well  as  of 
nature's  protective  influence  over  investing  membranes.  (See  Figs. 
130  to  138  inclusive). 

Imparting  anatomical  form  to  the  approximal  sides  of  crowns 
in  their  construction  provides  the  V-shape  spaces  so  essential  for  the 
gum  septa,  furnishes  protection  on  the  labial  and  buccal  sides  to  the 
gingival  tissue,  is  esthetic  in  effect;  and  the  contour  given  the  lingual 
side  restores  the  natural  shape,  which  is  the  one  most  agreeable  and 
suitable  for  the  tongue. 

Correct  reproduction  of  the  occlusal  surface  and  of  the  peripheral 
walls  distributes  the  force  of  occlusion  proportionately. 

Occlusion 

Anatomical  occlusion  in  crown-work  is  a  basal  requirement,  as  it 
influences  the  future  health,  efficiency  and  permanency  of  the  teeth 
crowned.  The  principle  of  the  occlusal  planes  should  be  kept  well  in 
mind,  and  as  much  as  possible  followed,  Incisal"  edges  and  occlusal 
surfaces  with  their  sulci  should  be  formed  and  placed  as  nearly  anatom- 
ically correct  as  the  occlusion  of  the  antagonizing  teeth  will  allow  or 
alteration  of  their  surfaces  permit.  Unevenly  applied  or  excessive 
occlusal  pressure  attributable  to  faulty  construction  is  conducive  to 
lesion  of  the  peridental  membrane,  of  the  crowned  teeth  or  roots  or 
their  antagonists. 

Approximal  Contact. — The  knuckling  of  adjacent  occlusal  surfaces 
the  one  to  the  other  is  absolutely  demanded.  When  imperfectly  per- 
formed, invasion  and  pressure  of  particles  of  food  in  mastication  are 
Hable  to  occur,  which  is  more  or  less  injurious  to  the  gum  septa  and 
productive  of  disease  of  the  pericementum. 

In  a  normal  state  of  occlusion  of  the  teeth  the  force  of  mastication 
is  received  in  an  upward  outward  direction  on  the  lingual  and  incisal 


PRINCIPLES  INVOLVED  IN  CROWN-WORK  ill 


Fig.   120. 


Fig.  121. 


Fig.  122. 


Fig.   123. 


112  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

surfaces  of  the  six  upper  anterior  teeth,  and  inwardly  in  an  opposite 
direction  on  the  incisal  and  labial  surfaces  of  the  corresponding  lower 
teeth.  When  bicuspids  and  molars  are  evenly  occluded  the  force  is 
direct   (Fig.  120);  in  a  side   or  lateral  motion  of   the   mandible   the 


Fig.  124. 


Pig.    125. 


Fig.   126. — Viewed  from  the  lingual  side. 

force  is  delivered  in  the  corresponding  direction  against  the  occlusal 
surfaces  of  the  cusps  (Fig.  121).  This  lateral  force  upon  the  cusps  in 
mastication  is  proportionately  greater  when  the  cusps  are  long,  as  in 
Fig.  122,  and  it  can  be  modified  by  giving  them  the  entirely  practical 


PRINCIPLES  INVOLVED  IN  CROWN -WORK 


11.3 


but  shorter  form  with  shallow  sulci,  illustrated  in  Fig.  123.  This  result 
can  usually  be  accomplished  without  injuriously  aflfecting  the  appear- 
ance, and  the  work  can  be  materially  simplified  by  a  proportionate 
reduction  of  the  cusps  of  the  natural  antagonizing  teeth. 

As  the  cusps  of  the  bicuspids  and  molars  retain  them  in  proper 
alignment  with  their  antagonizing  teeth,  they  should  always  be  formed 
to  accord  with  an  outline  of  the  original  shape  of  the  natural  teeth. 
Figs.  124,  125  and  126  illustrate  normal  occlusion  of  the  natural  teeth. 

Malformed  Occlusal  Surfaces. — Fig.  127  shows  an  upper  bicuspid 
crown  with  a  malformed  occlusal  surface  of  a  shape  often  improperly 
given  in  a  case  of  close  occlusion. 


Fig.  127. 


Fig.  12J 


Fig.  129. 


The  result  in  time  is  that  the  crown  and  root,  because  of  the  gliding 
pressure  exerted  on  the  surface  of  the  crown,  are  pressed  outward  so 
that  the  stability  and  usefulness  of  the  crown  are  gradually  impaired 
and  finally  destroyed.  In  a  case  where  the  symmetry  and  appearance 
imperatively  demand  such  an  extension  of  the  labial  cusp,  the  displace- 
ment just  referred  to  will  be  prevented  by  giving  sufficient  length  to 
the  lingual  cusp  to  lock  the  crown  in  the  act  of  occlusion,  as  shown  in 
Fig.  128.  This  principle  may  be  advantageously  applied  in  the  con- 
struction of  crowns  for  the  six  anterior  teeth,  especially  the  cuspids, 
when,  owing  to  the  loss  of  the  posterior  teeth,  they  have  to  bear  the 
force  of  occlusion.  A  slight  shoulder  or  partial  cusp  will  materially 
lessen  the  effect  of  the  outward  gliding  pressure.  Fig.  129.  (See  Part 
IV,  Chapter  III.) 

Median  Line  of  Natural  Crown  and  Root. — In  the  treatment  of 
root-canals  and  especially  in  the  adjustment  of  incisor  and  cuspid  arti- 


114  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Fig.  130.   ; 


Fig.   131. 


Fig.  132. 


Fig.  133. 


Fig.  134. 


Pig.  137. 


Fig.  138. 


PRINCIPLES  INVOLVED  IN  CROWN-WORK  115 

ficial  crowns  or  teeth,  the  operator  should  be  guided  by  the  fact  that 
the  center  of  the  line  of  the  incisal  surfaces  and  cusps  is  always  located 
in  the  median  line  of  the  combined  natural  crown  and  root,  as  is  shown 
in  Figs.  130  to  134. 

The  Post  in  Relation  to  Canals  and  Roots. — The  original  forms  of 
the  canals  and  roots  of  the  teeth  should  be  studied  and  kept  well  in 
mind  in  reaming  the  canals  for  the  reception  of  posts.  The  pulp-canal 
is  located  in  the  central  section  of  each  root;  in  the  incisors  and  cuspids 
very  nearly  on  a  straight  line  between  the  apex  of  the  root  and  the  center 
of  the  incisal  edge  or  cusp.  (See  Figs.  130  to  134.)  This  fact  will 
materially  aid  in  determining  the  direction  or  angle  at  which  a  drill, 
bur  or  reamer  should  be  introduced  into  these  teeth.  The  same  prin- 
ciple may  be  considered  in  the  conduct  of  operations  on  superior  bi- 
cuspids, inferior  first  bicuspids,  the  buccal  roots  of  superior  first  and 
second  molars,  and  the  mesial  roots  of  inferior  molars,  making  due  al- 
lowance for  such  curve  of  the  root  as  may  exist,  should  the  instrument 
be  introduced  deeply  into  the  canal.  (See  Figs.  135  to  138.)  When 
the  natural  crown  of  a  root  in  normal  alignment  with  the  other  teeth 
has  been  nearly  or  entirely  lost,  the  angle  to  give  the  in- 
strument may  be  calculated  by  the  adjoining  teeth. 

The  reaming  should  be  so  conducted  that  while  the 
necessary  enlargement  is  effected,  the  root  is  weakened 
the  least  possible. 

Strength  is  most  required  on  the  approximal  sides  of 
the  upper  and  lower  six  anterior  roots,  as  the  pressure 
imparted  by  the  post  in  the  canal  is  almost  entirely 
received  in  either  a  lingual  or  labial  direction.  Proper 
reaming  of  the  canal  in  accordance  with  its  original 
shape  and  that  of  the  cervical  section  of  the  root  and 
the  forming  of  the  post  to  correspond  will  provide  the 
greatest  proportionate  strength  for  both  root  and  post. 

As  the  most  strength  in  a  post  is  developed  in  the 
line  of  its  greater   diameter,  a  properly  adjusted  post 
that  inclines  to  an  oval  form  for  the  incisors  and  especially 
the  cuspids  will  afford  greater  strength  than  a  round  one  composed  of 
the  same  quantity  of  metal.     Fig.   139  outlines  a  cuspid  root  and 
oval-shaped  post. 

Tapering  the  post  allows  it  to  be  introduced  deeper  into  the  canal 
without  excessive  reaming  than  if  it  is  made  of  a  uniform  diameter  or 
only  rounded  at  the  point.  The  point  of  the  post,  whatever  the  shape, 
should  be  immovably  fitted  or  anchored  in  the  canal,  especially  when 
the  remaining  portion  fits  loosely,  as  shown  in  Fig.  140. 


ii6 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Anchoring  the  point  deeply  into  the  canal  defines  its  position  and 
lessens  the  liability  of  fracturing  the  root  under  pressure. 

When  the  point  of  a  post  is  not  anchored,  as  shown  in  Fig.  141,  but 
merely  cemented  with  gutta-percha,  crown  and  post  are  likely  to  tilt 
under  continued  application  of  pressure,  as  seen  in  Fig.  142.  A  weak 
or  thin  post  is  liable  to  bend,  as  illustrated  in  Fig.  143.  Each  of  these 
conditions  causes  fracture  of  roots  carrying  post  or  dowel  crowns,  or  of 
crowns  with  very  small  or  improperly  adapted  posts  and  partial  collars. 


Fig.  140. 


Fig.  141. 


Pig.   142. 


Fig.  143. 


The  Post  in  Relation  to  Post  or  Dowel  Crowns. — A  post  or  dowel 
crown  without  a  collar  is  dependent  entirely  on  the  post  or  dowel  for 
attachment  and  support.  In  this  function  the  post  exerts  and  resists 
in  its  encasement  and  foundation — the  root — all  the  lateral  and  direct 
pressure  incident  to  mastication.  The  length,  shape  and  size  of  a 
post  should  therefore  be  regulated  accordingly.  A  post  in  a  root  dis- 
tributes applied  pressure  its  entire  length  along  the  walls  of  the  canal; 
consequently  in  the  use  of  a  long  post  a  proportionately  greater  area 
is  involved  than  with  a  short  one. 

Short  and  Long  Crowns. — The  greater  the  distance  from  the  end 
of  the  root  the  force  is  exerted,  the  greater  the  proportion  of  lateral 
strain  the  walls  are  subjected  to.  Therefore  the  shorter  the  crown  the 
less  is  the  leverage  or  pressure.  This  principle  is  made  clear  by  Fig. 
144.  The  incisal  edge  of  the  crown  which  ends  at  A,  will  not  exert 
through  the  post  so  great  a  proportion  of  pressure  on  the  root  in  masti- 
cation as  one  with  an  incisal  edge  at  B,  which  again  would  exert  less 
pressure  than  one  that  extended  to  C.  The  latter  would  especially 
suggest  the  use  of  a  long  post. 

When  the  occlusion  of  the  six  anterior  teeth  is  deep  and  close,  as 
shown  in  Fig.  145,— a  condition  termed  "close  bite," — the  crown  and 
teeth  or  crowns  as  they  occlude  exert  an  increasing  gliding  pressure. 
An  occlusion  of  this  character  always  demands  the  largest  and  longest 


PRINCIPLES  INVOLVED  IN  CROWN -WORK 


117 


possible  close-fitting  canal  post.  In  occlusions  occurring  nearer  the 
incisal  surface,  termed  "  open  bite, "  as  seen  in  Fig.  146,  the  pressure 
is  more  direct  and  proportionately  less  lateral  in  character. 


Fig.   145. 


Fig.  146. 


Principles  Governing  the  Constructionof  Root-Caps  without  Collars. 

A  cap,  plate  or  cope  as  variously  designated,  without  a  collar,  fitted  to 
a  flat  or  slightly  curved  end  of  a  root  does  not  afiford  a  positive  resistance 
to  lateral  pressure  in  supporting  a  crown.  This  resistance,  however, 
can  be  quite  effectually  accomplished  for  the  cap 
by  giving  a  deep  curve  to  the  surface  of  the  end 
of  the  root  at  the  lingual  side,  or  both  labial 
and  lingual  sides  combined — as  resistance  re- 
quirements suggest — which  will  be  proportioned 
to  the  length  of  the  post.  The  radius  or  dis- 
tance from  the  point  of  the  post  to  the  margins 
of  the  curved  or  convex  surface  of  the  end  of 
the  root  must  be  less  than  from  the  point  of  the 
post  to  the  surface  of  the  center  of  the  end  of 
the  root.  Consequently,  the  shorter  the  post, 
the  deeper  the  labial  and  lingual  edges  of  the 
curve  should  extend.  The  principle  is  demon- 
strated in  Fig.  147.  C  is  the  center  of  the  root  end;  D  a  long  post 
and  E  a  short  one.  BB  is  a  segment  of  a  circle  described  from  D 
and  AA  a  segment  of  a  circle  from  E.  The  beveling  or  curving  of 
the  root  end  should  be  extended  beyond  BB  for  a  post  like  D  and 
beyond  AA  for  a  post  like  E. 

Posts  in  Relation  to  Collar  Crowns. — In  collar  crowns,  as  the  end  of 
the  root  is  encompassed  by  the  collar,  the  principal  use  of  the  post  is  to 
retain  the  crown.     The  actual  length  and  size  of  the  post  required  for 


Fig.  147. 


Ii8  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

a  collar  crown  is  dependent  on  the  conditions  presented.  Deep,  sub- 
stantially fitted  collars  require  the  aid  of  only  a  moderate  post.  Nar- 
row or  partial  collars  when  applied  to  the  six  anterior  teeth  require 
proportionately  larger  posts  for  the  crowns,  approximating  in  size  to 
those  used  for  the  ordinary  post  or  dowel  crown. 

The  force  of  occlusion  being  distributed  over  the  entire  occluding 
surface  of  bicuspids  and  molars,  when  a  collar  is  applied  it  should  en- 
tirely encircle  the  root.  Crowns  on  these  roots  are  therefore  not  so 
dependent  for  security  on  posts  as  those  placed  on  the  six  anterior 
teeth.  A  substantial  properly  fitted  and  cemented  post  in  any  root- 
canal,  whether  or  not  attached  to  the  artificial  crown,  always  materially 
strengthens  the  root. 

Selection  of  Porcelain  Teeth. — Crown-  and  bridge- work  is  a  branch 
of  dental  prosthesis  which  requires  judgment  and  skill  in  the  selection 
of  porcelain  teeth  for  the  work  in  hand,  as  one  of  the  great  objects  in 
dental  art  should  be  to  conceal  art.  In  a  large  proportion  of  operations 
on  the  anterior  teeth,  the  result  must  be  studied  generally  as  much 
with  reference  to  appearance  as  to  utility.  In  size,  form  and  shade 
porcelain  teeth  selected  for  one  side  of  the  mouth  should  match  the 
corresponding  natural  teeth  on  the  other  side.  The  shade  should  be 
fully  as  dark,  never  lighter.  Uniformity  in  shade  of  the  different 
teeth  should  be  avoided.  Central  incisors  usually  require  to  be  the 
lightest  in  shade,  laterals  slightly  darker,  the  cuspids  darker  than  the 
laterals,  and  the  bicuspids  about  the  shade  of  the  laterals.  The  shades 
of  the  lower  teeth  vary  in  the  same  order  but  are  a  little  darker.  Ob- 
servation of  this  rule  in  selection  will  avoid  that  extreme  sameness  of 
shade  so  characteristic  of  artificial  teeth,  and  cause  them  to  more 
closely  approach  natural  teeth  in  appearance.  The  proper  and  suc- 
cessful performance  of  crown-work  operations  depends  largely  upon 
the  due  observance  of  the  principles  here  presented. 

Dependence  of  Crown-Work  Operations  on  Asepsis. — Crown-work 
in  the  restoration  of  badly  decayed  pulpless  teeth  or  roots  is  intimately 
associated  with  their  treatment,  more  especially  as  regards  the  estab- 
lishment and  future  maintenance  of  a  state  of  asepsis.  The  usefulness 
of  operations  depends  on  the  successful  assurance  of  this  condition. 
Recent  investigations  show  conclusively  that  ordinary  infection  of 
pulpless  teeth  and  roots  occurs  mostly  from  the  oral  cavity.  It  is 
therefore  clear  that  root-canal  filling  and  such  restoration  of  any 
portion  of  the  natural  crown  present  as  may  be  required  preparatory  to 
capping  should  be  so  conducted  as  to  offer  the  greatest  possible  ob- 
struction to  infection  from  that  source. 


CHAPTER  III 

SHAPING  TEETH  AND  ROOTS  FOR  CROWN-WORK 

LOCAL  ANESTHESIA — ADRENALIN  AND  COCAIN — INSTRUMENTS  USED — 
CROWNS  WITHOUT  COLLARS  AND  READY-MADE  PORCELAIN  CROWNS — 
COLLAR  CROWNS — PRINCIPLES  INVOLVED — PREPARATION  OF  TEETH 
OR  ROOTS  FOR  ALL-GOLD  COLLAR  CROWNS — COLLAR  CROWNS  WITH 
PORCELAIN  FACINGS — PARTIAL  COLLAR  CROWNS — SPECIAL  PREPA- 
RATION OF  BADLY  DECAYED  TEETH  OR  ROOTS — RESTORATION  \\1TH 
GOLD 

Local  Anesthesia. — The  shaping  of  roots  or  crowns  of  teeth  for 
crowning  operations  does  not  necessarily  call  for  the  use  of  general  or 
conductive  anesthesia,  In  the  proper  conduct  of  the  operation  the 
local  application  of  anesthetic  agents  is  usually  sufficient.  Anesthetic 
agents  so  applied  affect  the  gingivae  and  investing  membranes  but 
not  materially  the  dentin.  The  dentin  of  pulpless  roots  or  teeth  does 
not  require  desensitizing,  and  in  cases  of  teeth  with  vital  pulps  desen- 
sitizing is  either  not  desirable  or  only  permissible  to  a  limited  extent. 
When  teeth  are  so  sensitive  as  not  to  permit  proper  preparation,  or 
become  so  during  the  operation,  pulp  removal  is  suggested  to  avoid 
subsequent  lesions.  Under  general  and  conductive  anesthesia  the 
operator  is  unaware  of  the  exact  extent  of  the  sensitiveness  developed, 
but  after  the  anesthesia  has  passed  the  patient  becomes  conscious  of  it 
and  often  annoyingly  so.  In  the  use  of  local  anesthesia  the  same  care 
should  be  exercised  to  avoid  injury  to  the  investing  membranes  as 
though  sensation  were  present. 

Adrenalin  and  Cocain. — Tablets  No.  151:  Cocain  hydrochlorid 
}-i  grain,  Adrenahn  3^:^00  grain  (Parke,  Davis  &  Co.),  is  a  prompt  and 
effective  agent  for  local  anesthesia.  The  tooth  to  be  operated  on  is 
protected  from  the  saliva  with  cotton  rolls.  One  or  two  tablets  are 
broken  into  small  pieces  and  carried  with  the  point  of  a  thin  spatula, 
or  other  suitable  instrument,  well  under  the  free  margin  of  the  gum 
entirely  around  the  root  or  tooth.  The  moisture  present  under  the 
gum  is  generally  sufficient  to  dissolve  the  tablet  and  retain  it  in  position; 
if  not,  dampen  the  point  of  the  instrument  by  dipping  it  in  water. 
Protect  the  tooth  from  the  saliva  for  two  or  three  minutes,  then  remove 

119 


I20 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


the  cotton  rolls  and  have  the  patient  rinse  the  mouth  instantly.  In 
this  manner  the  action  of  the  cocain  is  mostly  confined  to  the  spot 
where  it  is  appHed  without  other  unpleasant  effect.^ 

Instruments  Used. — Carborundum  wheels,  such  as  are  illustrated 
in  Fig.  148,  are  used  to  grind  down  occlusal  surfaces,  portions  of  teeth 
and  ends  of  roots.  Thin  disks  of  vulcarbo,  straight  side  or  curved, 
as  shown  in  Fig.  149,  are  for  cutting  the  approximal  sides.  Points 
seen  in  Fig.  150  are  for  trimming  around  the  sides  of  crowns  at  or  close 


y 


u 


n 


to  the  cervix.  The  wheel-shaped  forms  in  Fig.  150  are  for  trimming 
such  parts  of  the  crown  or  root  as  they  can  reach.  Many  of  the  smaller 
points  may  be  used  to  advantage  in  the  angle  attachment  to  reduce 
parts  that  cannot  be  well  reached  by  them  when  in  the  straight  hand- 
piece. Trimmers  of  the  shapes  and  sizes  illustrated  in  Fig.  151,  made 
with  cross-cut  serrations  in  the  straight  or  angle  handpiece  are  ser- 
viceable for  rounding  corners  and  trimming  the  cervices  of  roots.     Fig. 

152  illustrates  a  triangular  point  that  can  be 
made  of  an  engine  bur  tempered  very  hard, 
each  of  the  edges  of  which  can  be  used  as  a 
scraper  in  a  hand  socket,  bracing  the  hand 
by  resting  the  thumb  on  the  adjoining  teeth. 
Files  and  serrated  scrapers  shaped  as  shown 
in  Fig.  153  are  useful  in  rounding  angular  cor- 
ners. Ottolengui  safe-side  root-facers  (Fig. 
154)  are  also  serviceable  for  leveling  the  end  of  a  root,  especially  under 
the  gum  margin.  For  giving  the  cervix  a  smooth  surface  on  the  approxi- 
mal sides  and  the  curves  to  the  other  sides,  medium  coarse,  then  fine 
carborundum-paper  disks  and  tape  should  be  used. 

Enamel  cleavers,  illustrated  in  Fig.  155,  are  also  used  to  remove  the 
enamel  entire.  The  removal  of  the  peripheral  ring  of  the  enamel  allows 
the  collar  to  be  accurately  adapted  and  fitted  to  take  the  place  of  the 
enamel  and  avoid  creation  of  a  shoulder.  Enamel  cleavers  should 
have  very  short  handles  to  afford  a  good  grip.  They  should  be  held 
^  The  author  has  used  this  agent,  as  described,  for  many  years  and  has  never 
experienced  any  result  unpleasant  enough  to  record. 

For  Conduction  Anesthesia,  see  "Materia  Medica,"  Prinz,  4th  Edition. 


Fig.  149. 


SHAPING  TEETH  AND  ROOTS  FOR  CROWN-WORK  I2i 

firmly  with  the  finger  resting  on  the  adjoining  teeth  to  avoid  slipping. 
Encircling  a  root  or  crown  at  intervals  with  a  wire  as  it  is  being  trimmed 
and  moving  it  up  and  down  will  indicate  points  of  irregularity. 

Wheels  and  points  should  be  kept  cool,  especially  when  grinding 
teeth  with  vital  pulps,  either  by  application  of  a  stream  of  cold  water 


or  by  frequently  dipping  in  ice-water.  A  piece  of  sponge  wet  with  ice- 
water  held  against  the  wheel  with  a  porte-carrier,  such  as  is  used  for 
carrying  a  small  piece  of  wood  in  cleaning  or  polishing  the  teeth,  of  the 
form  shown  in  Fig.  156,  is  admirable  for  the  purpose  and  also  protects 
the  tongue  and  cheek  from  injury  (Figs.  157  and  158).     Coating  the 


122 


CROWX-,  BRIDGE-,  AXD  PORCELAIN-WORK 


surface  of  a  disk  "^-ith  wax  on  the  side  opposite  to  the  one  used  mil  aid 
in  protecting  the  membranes. 

In  pulpless  teeth  the  use  of  excising  forceps  to  remove  the  crown 
should  be  avoided  unless  the  parts  are  first  deeply  ground  with  a  disk 


U     i 

1 

= 

;           ; 

i 

Fig.   151.         Fig.  152. 


Fig.  153. 


Fig.  154 


(Fig.  159)  and  will  admit  of  excision  without  shock  to  the  root  (Fig. 
160).  The  best  method  of  amputation  is  to  make  a  succession  of  holes 
with  a  fissure  bur.  This  will  permit  of  easy  removal  of  the  part  (Fig. 
161). 


Fig.   155. 

Crowns  Without  Collars  and  Ready-made  Porcelain  Crowns 

For  these  crowns  the  roots  are  ground  level  with  the  margin  of  the 
gum,  with  the  surface  of  the  labial  section  trimmed  a  little  below  it, 
especially  on  the  front  teeth,  if  it  is  desirable  to  conceal  the  joint  be- 
tween the  root  and  porcelain.  The  root-canal  is  shaped  to  the  form  of 
the  post  or  dowel  to  fit  it  tightly.     (See  Part  III,  Chapters  IV  and  XIV) . 


Collar  Crowns 

Principles  Involved. — The  principles  governing  the  shaping  of  the 
surface  of  a  natural  crown  or  root  for  any  style  of  artificial  crown  with 
a  collar  attachment,  require  that  all  parts  of  the  coronal  section  of  the 
natural  crown  present  shall  be  given  a  form  that  comes  entirely  within 


SHAPING  TEETH  AND  ROOTS  FOR  CROWS-WORK  123 


Fig.  157. 


Pig.  158. 


Fig.  156. 


r->. 


Pig.   159. 


Fig.   160.  Pig.   161. 


124  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

the  line  of  the  periphery  of  the  cervix.     Such  a  form  is  necessary  to 
admit  of  a  perfect  adaptation  of  the  cervical  section  of  the  collar. 

Preparation  of  Teeth  or  Roots  for  All-Gold  Collar  Crowns. — The 
coronal  section  of  a  natural  crown  to    be  prepared  is  usually  first 


Fig.  162. 


ground  on  the  incisal  or  occlusal  surface  with  as  large  a  carborundum 
wheel  as  the  case  will  conveniently  admit  and  avoid  injury  to  the 
adjoining  teeth  (Fig.  162).     Sufficient  tooth  structure  should  be  re- 


FiG.  163. 


moved  from  the  occlusal  surfaces  to  afford  space  for  any  applied  inter- 
vening plate  or  occlusal  cusps  and  reinforcements,  which  as  a  rule  in 
teeth  with  vital  pulps  is  one-sixteenth  inch;  and  in  pulpless  bicuspids 


Pig.  164.  Pig.  165. 

and  molars  is  a  little  beyond  the  line  of  the  points  of  the  occlusal  cusps 
of  the  antagonizing  teeth  when  occluded,  as  indicated  by  the  dotted 
line  in  Fig.  163.  The  approximal  sides  of  the  cervix  should  be  removed 
sufficiently  to  allow  a  free  space  between  the  gold  collar  when  adjusted 
and  the  cervices  of  approximal  natural  teeth  or  artificial  crowns,  to 


SHAPING  TEETH  AND  ROOTS  FOR  CROWN -WORK 


125 


make  room  for  the  gum  septa  (Fig.  164).  Teeth  with  vital  pulps  that 
will  not  admit  of  such  preparation  should  have  the  pulps  removed,  or 
some  other  method  besides  crowning  adopted. 
The  removal  of  the  approximal  sides 
should  be  first  started  at  the  occlusal  surface 
in  a  straight  line  to  the  cervix,  as  illustrated 
in  Fig.  164,  in  a  case  of  a  molar,  using 
vulcarbo  disks  straight-sided  or  cup-shaped 
to  get  the  angle    (Fig.    149).     Occasionally 

thin  safe-sided  separating  files  are  serviceable  to  avoid  injury  to  the 
contour  of  an  adjoining  tooth  in  starting  the  trimming.     Next,  as  the 


Fig.  166. 


Fig.  167. 

approximal  teeth  are  then  more  easily  avoided,  the  labial  and  lingual 
portions  are  reduced  with  small  carborundum  wheels  (Fig.  165),  and 


Fig.  168. 


vulcarbo  points   (Fig.    150)    in   the  straight  hand-piece   and   angle 
attachment. 

Pulpless  teeth  usually  require  complete  removal  of  the  enamel 
(Fig.  166).     When  a  tooth  contains  a  vital  pulp  and  a  portion  of  the 


126 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK, 


enamel  is  allowed  to  remain,  the  surface  of  the  enamel  should  be  leveled 
in  parallel  lines  as  far  as  the  edge  of  the  collar  is  to  be  extended  (Figs.  167 
to  169). 

In  preparing  incisors  and  cuspids  for  gold  cap-crowns  where  the 
pulp  is  to  be  preserved,  after  trimming  the  approximal  sides,  the  labial 
surface  and  incisal  edge  should  be  ground  down  as  much  as  possible, 
without  too  closely  approaching  the  pulp  or  subjecting  it  to  irritation; 
then  the  lingual  portion  at  an  angle  from  the  cervical  border  to  the 
incisal  edge,  enough  to  level  its  prominence  of  contour  and  furnish 
ample  space  between  it  and  the  antagonizing  teeth  for  the  metal  that 
will  cover  the  surface  (Fig.  167). 

Bicuspids  and  molars,  with  or  without  pulps,  for  all-gold  cap-crowns 
should  have  as  much  of  the  natural  crown  left  as  may  be  without  ob- 
structing the  proper  and  accurate  adaptation  and  adjustment  of  the 


Pig.  169. 

crown  (Figs.  168  and  169).  A  shghtly  tapering  form  is  advisable:  a 
thimble  shape  is  unnecessary  and  undesirable.  While  the  approximal 
sides  may  incline  toward  the  occlusal  surface,  the  other  sides  should  be 
more  nearly  parallel.  This  form  is  preferable  in  the  constructing  of 
the  crown  and  is  more  favorable  for  its  attachment. 

The  proportion  of  teeth  with  living  pulps  to  which  gold  cap-crowns 
should  be  applied  is  small.  The  exceptions  are  cases  in  which  extensive 
decay  has  involved  considerable  of  the  coronal  section  of  the  tooth  and 
caused  more  or  less  calcification  of  the  pulp.  The  preparation  of  these 
cases,  of  which  Fig.  170,  a  bicuspid,  and  Fig.  171,  a  molar,  are  typical, 
consists  in  the  trimming  of  the  decomposed  enamel  at  the  approximal 
sides,  a  moderate  reduction  of  the  occlusal  surface,  and  the  removal  of 
enough  from  the  contour  of  the  labial  and  lingual  surfaces  to  allow  the 
edge  of  the  collar  to  pass  over  and  be  closely  adjusted  at  the  cervical 
section  under  the  free  margin  of  the  gum.  Trimming  of  the  tooth  for 
the  purpose  of  deeply  embedding  the  edge  of  the  collar  under  the 


SHAPING  TEETH  AND  ROOTS  FOR  CROWN-WORK  127 

gingival  margin,  so  that  it  will  closely  approach  the  pericementum,  is 
unnecessary  and  not  advisable  unless  some  special  condition  suggests 
it.  Irritation  of  the  pericementum  from  impingement  of  the  collar 
will  result  in  recession  of  that  membrane,  also  of  the  gingival  margin 
and  the  exposure  of  the  edge  of  the  collar.  Figs.  172  and  173  show  a 
typical  bicuspid  and  molar  prepared  for  the  adaptation  of  metallic 
cap-crowns,  the  natural  teeth  having  been  trimmed  and  the  cavities 
sterilized  and  filled  with  amalgam  or  oxyphosphate  covered  with 
amalgam. 

Extremely  short  teeth  and  teeth  slightly  embedded  in  the  t'ssues, 
as  many  third  molars  are,  when  capped  without  removal  of  their  pulps, 
do  not  require  as  much  shaping  as  long  bicuspids  and  first  molars. 

It  should  be  borne  in  mind,  however,  that  excessive  or  unneces- 
sary cutting  away  of  the  enamel  and  dentin  of  teeth  with  living  pulps, 
leaves  them  in  an  extremely  sensitive  condition,  and  is  likely  to  result 
subsequently  in  some  serious  lesion  of  the  pulp.  Slight  sensitiveness, 
such  as  may  be  caused  by  excessive  shaping,  is  relieved  by  drying  the 


Fig.   170.  Fig.  171.  Fig.   172.  Fig.   173. 

exposed  dentin  with  hot  air  and  applying  carbolic  acid  two  or  three 
times  as  required.  When  this  treatment  is  not  suflEiciently  effective, 
a  temporary  cap  of  pure  gold  about  gage  No.  34  can  be  quickly  con- 
structed and  cemented  on  with  gutta-percha.  A  small  quantity  of  a 
compound  of  oil  of  cloves,  carbolic  acid  and  chalk  (Part  II,  Chapter  I), 
placed  in  the  center  of  the  cap  acts  as  a  sedative  agent. 

Collar  Crowns  with  Porcelain  Facings. — For  collar  crowns  for  the 
anterior  teeth  the  end  of  the  root  is  left  projecting  at  the  lingual  side 
in  removable  bridge  operations,  and  the  surface  of  the  end  ground  on 
an  inclined  plane  towards  the  gum  margin  at  the  labial  section,  as 
shown  in  Fig.  174.  For  ordinary  crowning  operations  the  projecting 
end  is  usually  preferably  squared-off,  as  shown  at  Fig.  175.  Bicuspids 
which  are  to  have  porcelain  facings  are  given  the  same  general  form 
(Fig.  176).  In  preparing  the  roots  of  incisors,  cuspids  or  bicuspids  it  is 
advisable  to  allow  the  labial  section  of  the  end  of  the  root  to  project 
slightly  beyond  the  gum-margin  until  the  collar  has  been  fitted,  after 
which  it  can  be  reduced. 


128 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Partial  Collar  Crowns. — Shape  the  approximal  and  lingual  sides  of 
the  root,  leaving  the  labio-cervical  side  intact  (Figs.  177  and  178). 
The  surface  of  the  end  of  the  root  is  shaped  as  for  the  full  collar. 


Fig.  174- 


Fig.  175. 


Fig.   176. 


Fig.  177. 


When  necessary,  the  incisal  edges  and  occlusal  cusps  of  antagoniz- 
ing teeth  should  be  sufficiently  reduced  to  furnish  ample  space  for  the 
artificial  crowns,  and  to  favor  them  in  occlusion.  Accord- 
ingly, when  a  tooth  is  to  be  crowned  that  is  broken  down 
and  shortened  by  long-continued  decay  and  the  antagoniz- 
ing teeth  have  consequently  become  elongated,  they  should 
be  reduced  in  length  as  much  as  they  properly  can  be  to 

proportion  the  space  between  them  and  the  artificial  crown 
Fig   178    '^     -^  '■ 

A,  Cervico-  ^nd  improve  the  occlusion.     When  the  approximal  teeth. 

labial     sec-  are  Crowded  against  and  overhang  the  end  of  a  root  so  that 

intact.  the  space  for  the  artificial  crown  at  the  occlusal  surface  is 

narrower  than  at  the  cervical  section  measured  from  mesial 

to  distal  side,  the  approximal  teeth  should  be  pressed  back  to  furnish 

space  to  permit  the  adjustment  of  a  straightsided  collar  on  the  pre- 


Fig.  179. 

pared  root  and  proper  space  between  the  collar  and  the  sides  of  the 
roots  of  the  adjoining  teeth.  The  approximal  teeth  can  be  pressed 
back  by  packing  on  eacH  side  of  the  root  with  gutta-percha,  or  by  the 


SHAPING  TEETH  AND  ROOTS  FOR  CROWN-WORK 


129 


insertion  of  a  piece  of  orange-wood  notched  on  the  end,  that  tightly 
fits  the  space,  the  wood  to  be  removed  and  increased  in  length  at 
intervals  by  the  operator  or  patient  (Fig.  179).  In  cases  that  prop- 
erly suggest  it,  a  small  portion  of  the  interfering  surfaces  may  be  re- 
moved and  polished,  as  shown  in  typical  cases  in  Figs.  180  and  181, 
so  as  to  allow  parallel  or  slightly  flaring  sides  to  the  collar. 


Pig.  180. 

Special  Preparation  of  Badly  Decayed  Teeth  or  Roots. — The  tem- 
porary exposure  of  the  end  of  a  root  or  of  the  cervical  portion  of-  a 
crown  for  the  purpose  of  permitting  restoration  of  the  part  with  an 
amalgam  or  gold  inlay  to  simplify  a  crowning  operation,  especially  in 
the  adaptation  of  a  collar,  is  effected  by  inserting  in  the  pulp-chamber 
or  the  root-canal  a  cone-shaped  piece  of  gutta-percha  large  enough  to 
admit  of  a  portion  being  brought  over  against  the  investing  membranes 
to  compress  them  for  a  day  or  more.  In  some  cases  to  secure  attach- 
ment for  the  gutta-percha,  a  wire  post  or  a  flat-headed 
tack  may  be  cemented  temporarily  in  the  root  with 
gutta-percha  and  the  gutta-percha  packed  around  it. 
Roots  can  thus  be  exposed  to  the  border  of  the  alveolar 
process,  if  desired,  by  renewals  of  the  packing.  In  bicus- 
pids and  molars,  when  the  decay  extends  on  the  cervLx 
further  than  will  the  edge  of  the  artificial  crown  or  collar, 
the  gum  margin  should  be  compressed,  as  already  des- 
cribed (Figs.  73. and  74),  the  decay  removed,  retaining 
pits  made  and  the  cavity  filled  with  amalgam  shaped  to  the  con- 
tour required  (Fig.  182).  In  such  cases,  when  the  pulp  is  vital,  the 
amalgam  will  generally  be  in  close  proximity  to  it  and  the  cavity  fre- 
quently of  a  form  unfavorable  to  the  retention  of  the  filling.  To  avoid 
irritation  from  thermal  changes  and  to  better  retain  the  filling,  a  moder- 
ately thin  mixture  of  oxyphosphate  may  be  first  placed  in  the  cavity, 
the  amalgam  then  pressed  into  it  and  the  oxyphosphate  forced  out  at 
the  margins,  where  the  amalgam  must  be  brought  into  direct  contact 
with  the  tooth  structure. 
9 


Fig.   182. 


I30  CROWN-  BRIDGE-  AND  PORCELAIN-WORK 

In  incisors  and  cuspids,  when  decay  has  deeply  destroyed  a  portion 
of  the  side  of  the  root,  a  tight-fitting  tube  of  platinum  veneered  with  a 
film  of  pure  gold — to  which  amalgam  will  readily  adhere — and  of 
such  size  as  to  admit  the  post  of  a  crown,  may  be  inserted  in  the  root- 
canal,  cemented  with  oxyphosphate  and  the  decayed  portion  on  the 
side  of  the  root  restored  with  amalgam  (Fig.  183  section).  A  cast 
gold  inlay  may  be  used  with  the  tube  instead  of  the  amalgam.  (Part 
III,  Chapter  II.)  The  post  of  the  crown  should  be  tapered  at  the  end 
and  inserted  in  the  canal  as  deeply  as  possible  in  the  sound 
portion  of  the  root  beyond  the  end  of  the  tube  to  gain  addi- 
tional strength  by  distributing  the  leverage  along  the  entire 
line  of  the  root.  When  the  amalgam  has  set,  it  should  be 
dressed  down  at  a  subsequent  sitting  evenly  with  the  sur- 
face of  the  root  and  polished, 
\    /  In  some  cases  a  better  method  is  to  fit  and  cement  a 

~  pointed  post  as  far  up  the  canal  as  it  can  safely  be  intro- 

duced, leaving  the  end  of  the  post  protruding  beyond  the 
gum.  Then  shape  the  side  and  end  of  the  root  with  amalgam  or  a 
gold  inlay,  and  cap  with  a  gold  or  platinum  porcelain  jacket  crown 
or  one  entirely  of  porcelain  (See  Crowning  in  Cases  of  Abrasion,  and 
Part  VI,  Chapter  VII).  Fig.  184  shows  a  typical  cuspid  and  bicuspid 
of  this  character. 

When  an  incisor  or  cuspid  crown  post  is  to  be  inserted  and  the  root- 
canal  is  enlarged  from  decay  or  excessive  reaming,  the  defect  in  relation 
to  the  post  of  the  crown  can  be  remedied  in  the  following  manner: 
Fit  a  tapering  post  of  medium  size  with  the  point 
reaching  the  extremity  of  the  canal.  Close  the 
foramen  with  a  very  small  point  of  gutta-percha, 
so  that  it  will  not  interfere  with  the  insertion  of  the 
post.     Fill  the  canal  with  a  thin  mixture  of  zinc    /MB"     ^""IB^ 

oxychlorid,  insert  the  post  and  when  the  cement     •■..., -.^T.    / 

is  about  one-half  set  remove  it.  Instantly  wipe 
off  the  post  and  reinsert  it.  The  temporary  re- 
moval of  the  post  breaks  the  adhesion  of  the  cement  to  the  post  so  that 
when  the  cement  has  set,  the  post  can  be  removed  and  you  have  a 
close-fitting  socket  for  it.  Zinc-oxyphosphate  may  be  used  for  the  same 
purpose  by  veneering  the  post  with  chloro-gutta-percha  to  permit  re- 
moval when  the  cement  is  set.  The  oxyphosphate,  however,  does  not 
possess  the  antiseptic  properties  of  the  oxychlorid. 

In  setting  a  gold  cap-crown  on  a  badly  broken-down  tooth  or  root 
a  post  of  either  clasp-gold,  platinum  or  iridio-platinum  wire  (Fig.  185) 
should  be  fitted  to  the  root-canals  (Figs.  186  to  188).     The  end  can 


SHAPING  TEETH  AND  ROOTS  FOR  CROWN -WORK 


131 


be  bent  or  a  piece  of  gold  or  a  globule  of  gold  melted  to  it.  The  post 
should  then  be  barbed,  the  point  fastened  in  the  root  with  a  little  oxy- 
phosphate  or  zinc  oxychlorid  and  the  crown  built  about  two-thirds  its 
length  with  a  quick-setting  amalgam,  to  be  shaped  when  hard  and  then 
slightly  notched  to  furnish  a  better  attachment  for  the  cement  with 
which  the  cap  is  set.  Rolling  the  wire  used  to  form  the  post  under  the 
flat  side  of  a  file  before  using  will  uniformly  roughen  the  entire  surface 
in  a  manner  most  favorable  to  the  adhesion  of  the  cement.  Screws 
may  be  used  as  posts  to  support  the  amalgam,  but  cemented  posts  are 
preferable.  A  previously  made  and  properly  fitted  collar  of  thin  cop- 
per plate  about  gage  No.  35  may  be  used  to  support  the  amalgam 
while  setting. 

Restoration  with  Gold.— The  restorations  described  can  be  eflfected 
with  gold  casting  instead  of  amalgam.    Gold  is  preferable  as  being  more 


1 


Pig.  185. 


Pig.  186. 


Fig.  187. 


Pig 


compatible  to  dentin,  especially  in  cases  where  decay  or  a  fracture  of  the 
delitin  extends  so  far  under  the  gum  margin  that  a  collar  cannot  be 
properly  applied  to  entirely  cover  the  part,  and  where  an  acid  condition 
of  the  mouth  exists.  In  such  cases  the  post  is  first  heated  and  veneered 
with  sticky  wax,  then  surrounded  with  inlay  wax,  adjusted  to  posi- 
tion in  the  canal  and  the  wax  pressed  and  shaped  to  the  desired  form. 
Fig.  189  shows  the  post  of  a  central  incisor  shaped  with  inlay  wax  in- 
stead of  amalgam  ready  for  investment  for  casting  (Part  III,  Chapter 
XVII).  The  same  result  can  be  obtained  by  the  indirect  method  by 
taking  an  impression  with  compound  placed  on  the  platinum  post,  re- 
moving the  post  in  position  in  the  compound,  and  making  an  amalgam 
die. 

For  the  use  of  porcelain  in  root  restoration  see  Part  VI. 


CHAPTER  IV 

THE  ALL-PORCELAIN  POST  CROWNS 

ALL-PORCELAIN  DETACHED-POST  CROWNS — PREPARATION  OF  THE  ROOT 
END — THE  S.  S.  WHITE  DETACHED-POST  CROWN — PREPARATION 
OF  THE  ROOT — DIRECT  METHOD  OF  FITTING  THE  CROWN — INDIRECT 
METHOD — ^THE  DAVIS  CROWN — THE  JUSTI  SHOULDER  PIN  CROWN — 
ash's  TUBE  TEETH  AND  CROWNS — EXAMINATION  OF  THE  PERIPHERY 
OF  A  PORCELAIN  READY-MADE  CROWN — REMOVAL  OF  EXCESS  OF 
PORCELAIN  AT  THE  PERIPHERY — CEMENTATION — REMARKS  ON  THE 
USE  OF  READY-MADE  PORCELAIN  CROWNS  AND  CROWNS  WITHOUT 
COLLARS 

The  all-porcelain  post  crowns  in  use  at  the  present  time  are  the 
result  of  progressive  development  of  this  branch  of  the  art  from  what 
was  originally  styled  the  porcelain  "pivot  tooth. "  For  this  reason  and 
because  of  their  simplicity  of  construction  and  application  they  will  be 
described  first. 

All-porcelain  post  crowns  are  used  by  many  dentists  almost  ex- 
clusively, with  the  exception  of  the  occasional  insertion  of  an  all-gold 
cap-crown  on  a  posterior  tooth.  The  reasons  for  this  are  the  greater 
intricacy  of  the  construction  of  gold  crowns  and  personal  objections  to 
crowns  with  collars. 

The  advocates  of  the  all-porcelain  post  crown  claim  for  it  natural 
appearance  owing  to  translucency,  the  lingual  aspect  not  being  covered 
with  metal,  restoration  of  contour,  strength  and  cleanliness,  together 
with  simplicity  of  construction  and  easy  adaptation  and  attachment 
to  the  root,  to  which  the  crown  is  hermetically  sealed. 

All-Porcelain  Detached-Post  Crowns 

In  this  style,  which  is  the  one  now  most  largely  used,  the  crown  is 
attached  to  the  root  by  a  post,  one  end  of  which  is  cemented  in  the  root 
and  the  other  in  the  crown,  such  as  the  S.  S.  White,  Davis,  Justi  and 
Ash. 

Crowns  in  which  the  post  is  to  be  cemented  admit  of  alignment  with 
the  other  teeth  more  easily  than  those  baked  with  the  post  in  position. 
The  attachment  of  the  crown  to  the  post,  however,  is  not  as  reliable 

132 


THE  ALL-PORCELAIN  POST  CROWNS 


133 


in  close  "bites"  when  cemented  as  when  baked  in  the  porcelain  like  the 
Logan. 

The  requirements  for  success  in  the  use  of  all  porcelain  detached- 
post  crowns  are: 

First. — A  strong,  accurately  fitted  post,   the  presence    of  which 
demands  the    least   possible  removal   of    root    structure,    ,      *     ^ 
thereby  retaining  the  greatest  amount  of  strength  for  re- 
sistance in  occlusion  and  mastication. 

Second. — Absolute  adaptation  of  the  surface  of  the  base 
of  the  crown  to  the  surface  of  the  root  end  or,  in  other 
words,  a  close  joint. 

Third. — Perfect  alignment  of  the  sides  of  the    »     *     * 
cervical  section  of   the  crown  to  that  of   the 
root. 

Fourth. — Correct  occlusion  of  the  antagoniz- 
ing teeth,  by  which  abnormal  pressure  is 
avoided. 

Preparation  of  the  Root  End. — The  prepara- 
tion of  the  canal  and  end  of  the  root  to  receive 
and  retain  posts  is  about  the  same  for  all  the 
different  styles  of  ready-made  porcelain  crowns. 
The  length  of  the  root-canal  is  first  measured 
with  a  root-canal  probe  or  plugger.  A  small  disk  of  rubber-dam  per- 
forated and  slipped  up  on  the  shank  of  the  instrument  can  be  used 
as  a  gage  by  adjusting  the  disk  to  the  end  of  the  root.  By  this  means 
the  proper  length  for  the  post  is  ascertained.  The  dimensions  of  the 
root  determine  the  size.  Fill  that  part  of  the  end  of  the 
mal  that  will  not  be  occupied  by  the  post;  enlarge  the 
mal  with  Gates-Glidden  drills  as  deep  as  required  to 
commodate  the  length  of  the  post  for  the  crown  that  is 
)  be  mounted.  Next,  with  a  gage-plate  determine  the 
ze  of  the  post  and  with  small-size  fissure  burs  and  proper 
ze  root-reamers  (Fig.  190)  gradually  ream  the  canal  to  a 

\.  jrm  and  dimension  into  which  the  post  will  fit  closely  (Fig. 
191).  For  the  anterior  teeth  the  end  of  the  root  is  trimmed 
to  the  gingival  margin,  slanting  slightly  below  it  at  the 
labial  side  to  hide  the  intended  union  of  porcelain  with 
root.  This  requires  the  removal  of  the  enamel  at  the 
cervico-labial  section  but  not  always  around  the  entire  periphery  of 
the  root.  This  is  best  done  after  reduction  of  the  end  of  the  root 
with  large  carborundum  wheels,  by  the  use  of  smaller  sized  wheels  and 
points  or  with  safe-side  root-facers  (Fig.  192).* 


Fig.   190. 


Fig.   191. 


134 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


In  these  operations,  as  likewise  in  others,  posts  of  platinum  and 
gold  or  iridio-platinum  are  preferable  to  those  made  of  alloys  that 
contain  a  large  percentage  of  the  baser  metals,  as  the  ultimate  corro- 
sion of  the  latter  tends  to  impair  and  weaken  the  dentin. 

The  S.  S.  White  Detached-Post  Crown. — This  crown  possesses  the 
main  features  of  the  Logan  crown,  from  which  it  differs  in  having  the 
post  detachable  (Fig.  193). 


Pig.   192. 


Fig.   193. 


Pig.   194. — Enlarged  Posts. 
A,  I-beam;  B,  round. 


The  base  is  cupped  out  to  receive  the  post,  with  a  recessed  shoulder 
for  the  collar.  This  cup-shape  form  leaves  only  a  narrow  rim  of 
porcelain  at  the  base  of  the  crown  to  be  ground  to  fit  it  to  the  surface 
of  the  end  of  the  root. 

The  post  is  made  in  two  forms,  I-beam  shaped  and  round  (Fig. 
194).     Each  style  is  made  in  two  sizes, large  and  small  (Fig.  195).     The 

I-beam  post  is  similar  in  form  to  the  post 
of  the  Logan  crown.  Both  it  and  the 
round  post  taper  toward  the  point.  The 
root  section  of  each  style  is  grooved  and 
the  portion  that  enters  the  crown  has 
small  flanges  with  a  large  one  that  rests 
on  the  shoulder  of  the  cup  and  being  close 
to  or  against  the  root  end  prevents  movements  of  either  the  post  or 
crown. 

Preparation  of  the  Root. — The  root  is  prepared  the  same  for  either 
the  direct  or  indirect  method.  The  canal  is  opened  up  with  a  twist 
drill  to  the  proper  depth,  and  large  enough  to  permit  the  easy  entrance 
of  an  Ottolengui  reamer  (Fig.  191).  Shape  the  canal  with  the  reamer 
to  conform  generally  to  the  root  section  of  an  S.  S.  White  detached- 
post,  tapering  toward  the  apex,  with  the  labio-lingual  diameter  greater 
than  the  mesio-distal  for  an  I-beam  post.  Then  with  a  root-facer  give 
the  end  of  the  root  labio-linguaUy  a  rounded  open  V  shape  (Fig.  192). 


Side 
view 


No.  I   No.  2    No.  3  No.  4 
Fig.  195. 


THE  ALL-POkCliLAtN  PO^f  CROlVM 


135 


t)irect  Method  of  Fitting  the  Crown.— To  fit  the  crown  to  the 
prepared  root  grind  freely  as  indicated,  an  operation  that  is  greatly 
facilitated  because  the  cup  shape  of  the  cervical  portion  leaves  only  a 
comparatively  thin  wall  of  porcelain  to  cut  away.     At  this  stage  of 


A  B  C  D 

Fig.  196. — Actual  size.  A,  Detached-post  crown,  cuspid,  fitted  to  root;  B,  the 
same,  sectional  view;  C,  Detached-post  crown,  bicuspid,  fitted  to  root;  D,  the  same, 
sectional  view,  showing  the  splitting  of  the  post  for  a  bifurcated  root. 

the  fitting  the  use  of  a  disk  of  articulating  paper  will  simplify  and 
facihtate  the  operation  by  marking  on  root  and  crown  the  point  of 
contact. 

Another  method:  Dry  the  end  of  the  root,  rub  a  carbon  pencil 
point  over  it  and  press  the  porcelain  against  it.     After 
fitting  the  crown,  adjust  the  post  to  root  and  crown. 
The  shoulder  in  the  recess  is  intended  as  a  bearing  for 
the  circular  flange  of  the  post  to  distribute  the  stress. 

In  cementing  the  crown  in  position,  the  post  can  be 
fixed  into  the  root  first  or  into  crown  and  root  together, 
according  to  the  preference  of  the  operator. 

The  requirements  for  a  lasting  operation  are  a  per- 
fect fit  and  a  reliable  cement  (Fig.  196).  Fig.  197 
shows  well-fitted  and  articulated  crowns. 

Indirect  Method. — After  shaping  the  root  as  in  the 
direct  method  and  fitting  the  post,  warm  the  root  sec- 
tion of  the  post  and  veneer  it  with  wax,  flowing  it  into 
the  grooves,  and  adjust  the  post  in  the  canal.  Next 
take  a  "bite"  in  wax  and  then  an  impression  in  com- 
pound, which  will  remove  the  post  in  position.  Pack 
amalgam — True  Dentalloy- — into  that  portion  of  the 
compound  impression  which  represents  the  end  of  the 
root  and  sides  of  the  approximal  teeth,  in  quantity  suf- 
ficient to  entirely  cover  the  form  of  the  crown  end  of  the  post,  then  fill  in 
the  remainder  of  the  impression  with  plaster.  The  model  must  be  allowed 
to  remain  long  enough  for  the  amalgam  to  set  before  separation.  The 
result  will  be  a  combined  plaster  and  amalgam  (metallic)  model,  an 


Pig.   197. 


136 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


exact  replica  of  the  root  and  of  the  approximal  teeth  with  the  post  in 

position  (Fig.  198).  An  articulating 
model  is  then  made.  With  these 
models  the  proper  crown  can  be 
selected  and  the  fitting  done  ac- 
curately. The  wax  on  the  surface 
of  the  post  will  allow  it  to  be  re- 
moved easily.  In  fitting  the  crown 
to  the  model  by  slight  pressure  and 

lateral  movement,  the  places  to  trim  will  be  distinctly  marked  on  the 


Fig.  199. 


porcelain  by  the  amalgam.     The  countersink  in  the  crown  is  of  suf- 
ficient  diameter  to  permit  the  post  to  be  set  at 
various  angles,  and  provides  room  for  any  necessary 
body  of  cement  beside   the  porcelain,   which   is 
roughened  to  insure  it  a  firm  attachment. 

In  the  use  of  detached-post  crowns,  when  neces- 
sary for  some  special  purpose,  the  hole  in  the  por- 
celain may  be  enlarged  or  its  angle  changed  slightly 
with  carborundum  points  or  steel  points  charged 
with  carborundum  paste.  In  this  manner  the  S.  S. 
White  Detached-Post  Crown  can  be  readily  adapted 
as  a  jacket  crown  (Fig.  199).  (See  Part  VI, 
Chapter  VIII.) 

The  Davis  Crown. — This  crown  has  a  concave 
base,  in  the  center  of  which  is  a  depressed  rim  that 
affords  a  rest  for  the  shoulder  on  the  post.     A 
countersunk  cavity  extends  into  the  crown  sufficiently  deep  to  accom- 
modate the  projecting  end  of  the  post  (Fig.  200). 

The  post  is  made  of  German  silver  in  proportioned  sizes,  also  of 


Fig.  200. 


THE  ALL-PORCELAIN  POST  CROWNS 


137 


alloys  of  gold  and  platinum,  slightly  tapered,  corrugated  its  entire 
length  and  somewhat  flattened  on  one  side  to  prevent  rotation.     It 


1     11 


Pig.  201. 


Straight      Double     Offset 
Pronged 
Pig.   202. 


Small  Medium  Actual 
size 


Pig.  203. 


Pig.  204. 


has  a  shoulder  which  fits  the  floor  of  a  depression  in  the  base  of  the 
crown,  but  not  closely  at  the  sides^  to  permit  alignment. 
The  Davis  crown  is  selected,  fitted  (either  by  the 
direct  or  indirect  method)  and  cemented  to  the  root  in 
a  manner  similar  to  the  S.  S. 
White  Detached-Post  Crown, 
with  the  exception  that,  the 
Davis  crown  post  being  nearly 
round  requires  a  correspond- 
ingly reamed  canal.  Fig.  201 
shows  reamers  made  for  the 
purpose,  and  Fig.  202  straight, 
split  (for  double-rooted  bicus- 
pids), and  oif-set  center  posts. 
The  last  are  for  crowns  where  the  root-canal  and  the  hole  in  the  crown 
are  not  in  the  same  line,  as  shown  in  Fig.  203. 

The  Justi  Shoulder  Pin-Crown.— This 
crown,  illustrated  in  Fig.  204  is  very 
similar  in  construction  to  the  Davis.  The 
method  of  its  application  is  identical. 

Ash's  Tube  Teeth  and  Crowns. — These 
teeth  have  a  perforation  through  the  center 
with  a  thin  platinum  tube  baked  in  the 
porcelain.  They  are  supported  on  the 
root  by  a  fluted  post.  Figs.  205  to  207  show  teeth  and  post.  When 
the  crown  is  properly  ground  and  fitted,  the  base  is  to  be  countersunk 
sufficiently  to  receive  the  shoulder  of  the  pin.  The  pin  is  then  bent  so 
as  to  allow  the  crown  to  assume  its  proper  position  on  the  root.     The 


Pig.  205.     Pig.  206.   Pig.  207. 


138 


CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 


socket-handle  instrument,  shown  in  Fig.  208  is  the  most  suitable  for 
this  purpose.  The  attachment  of  the  crown  is  made  by  first  securing 
the  pin  in  the  crown  with  sulphur  or  soft  solder  and  then  cementing  the 
fluted  post  in  the  root-canal  with  either  gutta-percha  or  oxyphosphate. 
Figs.  209  to  214  illustrate  Ash's  dowel  crowns.  They  are  applied 
in  a  manner  similar  to  the  Davis  crown.  The  dowels  or  posts  are  made 
of  what  is  termed  "Dental  Alloy"  and  are  the  strongest  at  the  part 


tjJ 


Fig.  209. 


Pig.  210. 


Fig.  2X1. 


Fig.  212.  Fu,.  213.  Fig.  214. 

that  bears  the  greatest  strain — the  portion  where  the 
crown  joins  the  root. 

Examination  of  the  Periphery    of   a  Porcelain 
!'  U        Post  Crown. — When  a  crown  of  this  class  has  been 
fitted,  before  cementation  an  examination  should  be 
made  to  ascertain  whether,  as  is  a  common  occur- 
rence, the  base  of  the  cervical  section  extends  beyond  ^ 

9  .  1       ,  ,       Fig-  215. 

the  line  of  the  side  of  the  root,  formmg  a  shoulder, 
as  seen  in  Fig.  215.     Its  removal  is  frequently  neglected  in  the 
Fig.  208  insertion   of    these   crowns.     This    shoulder   forms   a   ledge 
which,  if  allowed  to  remain,  causes  and  maintains  a  septic  con- 
dition that  impairs  the  health  of  the  investing  membranes  and  is  liable 
to  cause  decay  of  the  end  of  the  root. 

Removal  of  Excess  of  Porcelain  at  the  Periphery.  ^ — This  is  easily 
and  accurately  done,  as  follows:  Warm  a  disk  of  pink  base-plate 
gutta-percha  with  a  large  hole  in  the  center  to  accommodate  the  post 
(A,  Fig.  216).  Wipe  the  surface  with  a  pellet  of  cotton  moistened  with 
chloroform  or  oil  of  cajuput;  warm  the  gutta-percha  and  press  it 


THE  ALL-PORCELAIN  POST  CROWNS 


139 


against  the  base  of  the  crown.  Gradually  heat  crown  and  gutta- 
percha until  too  hot  to  be  comfortably  held  in  the  fingers  and  press  to 
position  on  the  root,  chill  and  remove.  On  the  gutta-percha  will  be 
found  an  accurate  impression  (B)  of  the  end  of  the  root.  The  surplus 
gutta-percha  is  removed  to  the  surface  of  the  porcelain  with  a  sharp 
knife  (C),  and  then  the  porcelain  to  the  line  of  the  root,  as  indicated  by 
the  impression  in  the  gutta-percha,  with  a  carborundum  wheel  lightly 
pressed  and  rapidly  revolved  in  a  direction  which  will  not  disturb  the 
gutta-percha  (D).  During  the  grinding  the  crown  should  be  frequently 
dipped  in  ice- water.  One  or  more  adjustments  of  the  crown  and  gutta- 
percha should  be  made  on  the  root  and  the  sides  carefully  examined 
with  a  suitable  instrument.  After  removal  of  the  projecting  edge  of 
porcelain,  the  remainder  of  the  crown  should  be  trimmed  to  harmonize 
in  contour  with  the  neck,  and  the  surface  polished  with  fine  sandpaper 
disks  and  oxid  of  tin  (putty). 

Cementation. — These  crowns  are  generally  cemented  entirely  with 
zinc  oxyphosphate.     To    cement  a   detached-post  crown   the   root   is 


Pig.  216. 


protected  and  dried  with  hot  air.  The  cement  is  mixed  to  a  medium 
consistence,  worked  into  the  root-canals  and  the  countersunk  base 
of  the  crown,  A  portion  is  then  applied  to  the  surface  of  root  and 
crown,  and  the  crown  pressed  to  position  and  held  until  the  cement 
has  at  least  partly  set.  The  surplus  should  not  be  removed  until  it 
has  thoroughly  set,  as  the  cement  will  then  snap  off,  not  drag  from 
the  joint. 

In  cementing  all-porcelain  detached-post  crowns  the  preferable 
method  is  to  first  cement  the  post  and  then  instantly  place  the  crown 
without  cement  in  position  over  the  post  to  define  its  alignment  posi- 
tively. When  the  cement  has  set  then  cement  the  crown  to  the  post. 
Some  conditions  may  suggest  the  reverse,  i.e.,  the  cementation  of  the 
post  in  the  crown  first. 

Another  method  is  to  apply  a  disk  of  gutta-percha  to  the  base  of  the 
porcelain  or  leave  the  disk  on  the  crown  that  was  used  to  outline  the 
periphery  of  the  root  and  then  cement  the  post  in  the  root  and  crown 
with  oxyphosphate.     The  object  is  to  have  a  cement  at  the  joint  that 


I40  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

will  not  wash  out.     The  pink  base-plate  gutta-percha  is  the  most 
durable  for  the  purpose. 

Remarks  on  the  Use  of  Porcelain  Ready-made  Crowns  and  Crowns 
without  Collars. — All-porcelain  post-crowns  have  some  decided 
advantages.  They  are  especially  useful  in  many  case  where  an  inex- 
pensive or  easily  adjusted  crown  is  required,  or  where  some  pathological 
condition  limits  the  probable  durability  or  permanence  of  any  opera- 
toin.  In  the  insertion  of  porcelain  crowns  the  removal  of  the  whole 
or  a  part  of  the  natural  crown,  which  could  be  utilized  to  some  extent 
as  a  foundation  by  another  system,  has  given  rise  to  various  objec- 
tions. If  the  natural  crown  is  entirely  cut  away  the  pin,  or  post, 
upon  which  almost  the  entire  support  of  the  artificial  crown  is  thrown, 
exerts  great  leverage  in  the  root-canal  when  no  band  or  brace  is  present 
on  the  exterior  of  the  root  to  relieve  the  strain.  With  the  entire  force 
of  mastication  bearing  directly  upon  these  pulpless  roots,  whose  dis- 
integration is  slowly  but  continuously  progressing,  they  are  liable  to 
be  fractured  and  their  usefulness  as  a  foundation  ended.  These  facts 
and  the  lack  of  strength  incident  to  conditions  such  as  close  or 
abnormal  occlusions  are  the  principal  objections  urged  against  porcelain 
crowns  on  uncapped  roots  as  ordinarily  inserted. 


CHAPTER  V 

PORCELAIN-POST  CROWNS  WITH  METALLIC  BASE 

PORCELAIN  DETACHED-POST  CROWN  \\lTIf  CAST  BASE — DIRECT  METHOD — 
INDIRECT  METHOD — PORCELAIN  FACED  GOLD  POST  CROWN — ROOT 
END  BEYOND  GUM  MARGIN 

Porcelain  Detached-Post  Crown  with  Cast  Base. — Sometimes  the 
end  of  the  root  is  decayed  under  the  gum  margin  so  unevenly  that  the 
base  of  the  porcelain  crown  cannot  very  well  be  ground  to  properly 
fit  it  (Fig.  217).  In  such  a  case  a  cast  floor  or  cap  should  first  be  made 
and  applied,  upon  which  the  porcelain  crown  can  rest  and  to  which  it 
can  be  attached. 

Direct  Method. — Grind  the  exposed  portion  of  the  end  of  the  root 
well  under  the  gum-margin  and  remove  all  decay.     Pack  and  repack 


Fig.  217.        Fig.  218.  Pig.  219. 


Pig.  220. 


Pig.  221 


gutta-percha  in  the  canal  and  over  the  end  of  the  root  against  the  tissue 
for  a  few  days  to  properly  expose  the  parts.  Fit  an  iridio-platinum  post, 
or  an  S.  S.  White  or  Davis  post  of  the  same  metal,  well  up  into  the  canal. 
Grind  a  porcelain  detached-post  crown  to  fit  the  cervico-labial  section 
of  the  root,  leaving  a  V-shape  space  between  the  crown  end  and  the 
root  at  the  lingual  side  (S,  Fig.  218).  Vaselin  the  base  of  the  crown 
and  wipe  off  all  surplus;  heat  the  exposed  end  of  the  post  and  veneer  it 
with  sticky  wax.  Next  surround  the  end  of  the  warm  post  with  inlay 
wax;  insert  post  in  root;  dip  crown  in  warm  water  and  press  to  position. 
Trim  and  shape  the  wax  on  the  sides  and  chill  with  a  stream  of  cold 

141 


142  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

water.  Remove  the  crown  from  the  mouth,  then  the  post  with  the 
wax  attached  without  disturbing  its  form  (Fig.  219).  Insert  sprue  wire 
in  the  thickest  part  of  the  wax  (Fig.  220)  and  cast  with  pure  or  22- 
carat  gold.  Fit  casting  to  root  and  crown  to  casting,  poHsh  and  cement. 
Fig.  221  shows  the  finished  crown. 

Indirect  Method. — Fit  an  iridio-platinum  post  in  the  root  the  same 
as  for  the  direct  method,  Heat  the  post,  veneer  it  with  compound, 
wet  the  canal,  insert  and  withdraw  the  post  as  the  compound  hardens 
so  that  the  post  may  be  easily  inserted  and  withdrawn.  Take  a  "bite " 
in  wax  and  an  impression  in  compound  that  will  remove  the  post  in 
position.  Vaselin  the  end  of  the  post,  pack  in  amalgam  around  the 
impression  of  root  and  post,  and  run  the  remainder  of  the  impression 
with  plaster.  Adjust  "bite"  to  model  and  run  articulation.  Should 
the  cavity  on  the  side  of  the  root  extend  very  far  under  the  gingiva, 
instead  of  the  method  just  described  take  an  impression  of  the  root  and 
post  in  a  tube  and  make  an  amalgam  die  with  a  cone-shaped  shank. 
Take  an  impression  of  the  case  and  fit  the  die  in  the  impression  and 
make  models.  The  models  will  give  the  exact  form  of  the  root  and  the 
position  of  the  post  as  in  the  mouth.  Remove  the  post  from  the  die 
by  seizing  the  exposed  end  with  heated  pliers,  holding  themfor  a  moment 
on  the  post  to  warm  it.  Remove  any  compound  on  the  post  and  re- 
place the  post  again  in  the  model.  The  construction  of  the  crown  on 
this  model  is  identical  with  that  described  in  the  direct  method. 

Porcelain-Faced  Gold  Post  Crown 

This  form  of  construction  is  generally  confined  to  the  six  anterior 
teeth.  The  root  of  a  cuspid  will  be  taken  as  a  typical  case  to  illustrate 
the  construction. 

The  end  of  the  root  is  prepared  the  same  as  for  an  all-porcelain 
crown,  as  shown  in  Fig.  222.  No  peripheral  trimming  is  necessary. 
To  have  the  joint  of  the  porcelain  entirely  invisible  in  the  finished 
crown,  the  surface  of  the  end  of  the  root  should  be  trimmed  off  enough 
to  allow  for  the  thickness  of  the  metal  plate  that  will  cover  it,  especially 
at  the  labial  side,  and  thus  admit  placing  the  edge  of  the  porcelain  fac- 
ing well  under  the  cervico-gingival  margin. 

As  crowns  of  this  style  are  principally  supported  by  the  post,  it 
consequently  constitutes  an  important  factor.  Iridio-platinum  or 
gold-platinum  wire,  about  gauge  No.  13,  is  commonly  used,  but  the 
requirements  of  some  cases  call  for  it  much  lighter  or  heavier. 

The  root-canal  is  enlarged  with  a  reamer  and  the  orifice  well  counter- 
sunk.    A  piece  of  iridio-platinum  or  gold-platinum  wire,  that  has  been 


PORCELAIN -POST  CROWNS  WITH  METALLIC  BASE 


143 


rolled  under  a  file  and  tapered  off  to  a  point,  is  fitted  well  up  the  canal, 
gaged  its  full  reamed  diameter,  so  that  greater  strength  shall  be  ob- 
tained and  the  root  rendered  less  liable  to  longitudinal  fracture  from 
pressure  in  a  forward  direction  (Fig.  223).  A  post  of  the  exact  size  and 
shape  of  the  canal,  made  as  described  in  Chapter  VIII,  of  platinum  wire, 
foil  and  gold  (Figs.  316  to  317),  is  a  good  form  to  use  in  a  large  canal 
with  this  style  of  crown. 

A  piece  of  platinum  plate  in  size  slightly  larger  than  the  end  of  the 
root,  of  gage  No.  34  to  36 — the  smaller  the  root  the  thinner  the  plate — 
is  adapted  to  it  by  pressure  with  a  ball  of  cotton  or  the  soft  rubber  tip 
of  a  pencil;  or  an  impression  may  be  taken  of  the  end  of  the  root  with 
impression  compound,  an  amalgam  die  made  and  the  platinum  plate 
or  cap  first  stamped  in  a  swager.  (See  Part  III,  Chapter  XI.)  The 
platinum  is  then  burnished  to  the  surface  of  the  end  of  the  root  and  well 
into  the  countersunk  orifice  of  the  pulp-canal  and  punctured  with  a 
sharp-pointed   instrument.     The  point   of   the  post   is   next    pushed 


Fig.  222. 


Fig.  223. 


Fig.  224. 


through  the  perforation  to  position  in  the  canal.  When  the  post  is 
withdrawn  from  the  root,  the  platinum  generally  adheres  to  it.  A  par- 
ticle of  pure  gold  with  flux  is  put  in  the  joint  in  a  Bunsen  gas  flame. 
The  least  quantity  of  gold  that  will  unite  the  parts  should  be  used. 
If  the  post  does  not  fit  sufficiently  tight  to  remove  the  platinum,  it 
should  be  connected  fast  with  wax,  removed  and  invested.  When 
soldered,  the  post  and  plate  are  again  adjusted  in  the  mouth  and  the 
plate  malleted  and  burnished  to  the  end  of  the  root  so  that  the  edge 
of  the  root  shall  leave  its  imprint  on  the  platinum.  The  plate  on  being 
removed  should  be  trimmed  to  this  mark  and  again  burnished  on  the 
root.  The  post  is  then  cut  off  and  trimmed  and  a  porcelain  facing  fitted, 
backed,  the  incisal  edge  protected,  and  the  facing  cemented  with  wax 
in  position  on  the  cap,  as  described  in  Part  III,  Chapter  IX.  The  whole 
is  then  removed,  invested  and  soldered  with  20-carat  solder,  which 
should  be  melted  in  at  the  base  of  the  post,  as  the  strain  is  very  great 
at  this  point,  when  the  crown  is  in  use. 


144  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

The  crown  is  cemented  to  the  root  with  oxyphosphate  cement  or 
gutta-percha,  or  both  combined  (Fig.  224). 

Root  End  below  Gum-Margin. — The  crown  just  described  is  a 
suitable  form  for  application  in  cases  where  the  cervical  section  of  the 
end  of  the  root  because  of  either  decay  or  fracture  is  considerably 
below  the  surface  of  the  gum  and  does  not  admit  of  the  use  of  a  collar. 
In  such  cases  the  end  of  the  root  should  be  first  fully  exposed  with 
gutta-percha  fastened  in  the  orifice  of  the  root-canal  and  extending  over 
the  surface  of  the  end  of  the  root,  pressing  away  the  gingiva.  Under 
such  a  condition  shaping  the  plate  or  cap  to  the  form  of  the  root  by 
the  use  of  a  die  facilitates  its  adjustment. 


CHAPTER     VI 

A  TEMPORARY  CROWN 

Fit  into  the  root-canal  a  tapered  post  made  preferably  of  German 
silver  wire.  Let  the  post  extend  out  of  the  canal  about  one-eighth  of 
an  inch,  and  roughen  its  sides.  Perforate  a  disk  of  the  heaviest  pattern 
tin,  pure  gold,  gage  No.  28,  or  Hooo  platinum  foil,  with  the  post  and 
fit  to  the  end  of  the  root.  Fit  a  suitable  two-pin  vulcanite  porcelain 
tooth  to  the  disk;  groove  out  the  porcelain,  if  necessary,  to  fit  over  the 


Fig.  225. 


Pig.  226. 


post  (Fig,  225).  Wax  the  porcelain  tooth  to  the  disk  and  post,  remove 
and  invest  in  plain  plaster  of  Paris.  Remove  the  wax  with  boiling 
water  and  apply  a  little  muriate  of  tin  to  the  end  of  the  post.  In  the 
place  occupied  by  the  wax  (A,  Fig,  226)  flow  fusible  metal  which  melts 
at  not  less  than  200°  F,,  and  instantly,  while  the  metal  is  yet  in  a  molten 
state,  press  it  down  firmly  into  the  investment  with  the  finger  covered 
with  a  napkin,  cool,  remove,  trim  and  cement  on  the  root  with  gutta- 
percha that  softens  at  a  low  heat.^ 

1  This  method  of  soldering  combines  the  principle  of  casting  under  pressure. 


145 


CHAPTER  VII 
GOLD  COLLAR  CROWNS 

CONSTRUCTION  AND  ADAPTATION  OF  COLLARS — TO  MEASURE  THE  CIRCUM 
FERENCE  OF  A  ROOT  OR  TOOTH — A  DENTIMETER — TO  DETERMINE  THE 
WIDTH  OF  A  COLLAR — CUTTING  THE  PLATE  FOR  THE  COLLAR — TO 
SOLDER  THE  JOINT  OF  THE  COLLAR — SWEATING  METHOD — FITTING 
A  COLLAR  TO  ROOT  OR  TOOTH — PLATINUM  COLLAR — REINFORCED 
THIN  PLATINUM  COLLAR — PLATINUM-LINED  GOLD-PLATE  COLLAR — 
APPLICATION  OF  A  LOCAL  ANESTHETIC — COLLAR  CROWNS  HYGIEN- 
ICALLY  CONSIDERED 

This  style  of  gold  crown  includes  those  methods  which  involve 
banding,  capping  and  hermetically  inclosing  with  gold  the  end  of  a 
root  or  the  crown  of  a  tooth,  for  the  purpose  of  securing  stabihty  to 
the  artificial  crown,  preventing  fracture  of  the  root  and  decay  of  the 
parts.  This  method  possesses  much  practical  value  as  a  preserver  of 
tooth  structure  and  restorer  of  usefulness  to  the  teeth,  and  affords 
excellent  supports  for  bridge-work. 

Collar  crowns  of  which  the  part  that  essentially  constitutes  the  cap 
is  constructed  in  sections,  will  be  first  described. 

The  Construction  and  Adaptation  of  Collars. — This  may  be  termed 
the  fundamental  part,  as  on  its  skilful  and  proper  performance  depends 
the  usefulness  of  collar  crown  operations. 

Careful  study  of  the  different  forms  of  natural  crowns  and  roots 
and  of  the  anatomical  structure  and  relationship  of  the  contiguous 
parts  is  most  essential  for  the  perfection  of  construction  and  adaptation 
required  in  collars,  bands  or  ferrules,  as  they  are  variously  designated. 

Some  devices  and  methods  in  use  facilitate  this  operation,  but  its 
skilful  performance  can  be  attained  only  by  study  and  practice,  as  is 
proved  by  the  easy  and  perfect  manner  in  which  it  is  done  by  experts 
in  crown-  and  bridge-work  who  use  no  special  appliances  and  are 
guided  by  an  intuitive  perception  of  the  requirements  of  each  case. 

Gold  alloys  of  at  least  22  carats  containing  2  to  3  per  cent,  platinum, 
gage  No.  30,  are  given  the  preference  for  collars,  as  the  joint  can  be 
soldered  with  pure  or  coin  gold,  which  permits  use  of  a  high-grade 
solder  without  affecting  it.  U.  S.  gold  coin  is  not  so  much  used  as 
formerly,  as  the  10  per  cent,  copper  it  contains  tends  to  cause  oxida- 

146 


GOLD  COLLAR  CROWNS 


147 


tion  and  as  it  is  not  high  fusing,  it  requires  more  care  and  skill  in  its 
use  in  soldering  operations  than  plate  of  the  higher  fusing  alloys. 

The  size  of  the  cervix  of  the  root  or  dimensions  of  the  natural  crown 
to  be  capped,  whether  it  is  to  effect  only  restoration  of  the  crown  or  to 
give  support  to  bridge- work,  should  govern  the  choice  of  gage  of  plate 
to  be  used.  Cuspids  and  molars  require  a  heavier  plate  than  small 
laterals  or  lower  incisors,  and  in  all  forms  of  gold  caps  the  gage  should  be 
slightly  increased  when  they  are  to  support  bridge-work. 

To  Measure  the  Circumference  of  a  Root  or  Tooth. — The  natural 
crown  or  root  having  been  properly  prepared  is  measured.     For  the 


Fig.  227. 


Fig.  1228. 


Fig.  229. 


circumference  form  a  loop  of  copper  or  iron  wire,  gage  No.  30  or  31  by 
twisting  the  ends  together  with  the  pliers.  Slip  the  loop  over  the 
tooth  or  root,  press  the  wire  down  under  the  gum  margin  and  twist  the 
ends  with  the  pliers  until  the  loop  fits  tightly  at  every  point  (Figs. 
227  and  228).  Slip  off  the  loop,  extend  the  wire  and  cut  the  center 
opposite  the  twist,  then  extend  the  ends  lengthwise,  as  shown  in  Fig. 
229. 

The  Dentimeter. — A  dentimeter,  such  as  is  exhibited  in  Fig.  230, 
facilitates  measurements  with  wire.     The  ends  of  the  wire  are  passed 


Fig.  230. 


into  the  hole  in  the  point  of  the  head  and  out  through  the  openings 
which  are  cut  into  it  from  the  two  sides.  The  loop  thus  formed  is 
adjusted  around  the  tooth  or  root,  and  the  end  of  the  dentimeter  is 
pressed  against  the  root  at  the  gum  margin.  A  few  turns  of  the  den- 
timeter twist  the  loop  tight,  when  the  dentimeter  can  be  laid  aside 
and  the  loop  removed.  Teeth  and  roots  difficult  to  reach  at  the 
buccal  side  may  often  be  more  easily  reached  at  the  lingual. 


148 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


To  Determine  the  Width  of  a  Collar. — For  an  all-gold  crown  meas- 
ure from  the  occlusal  surface  of  the  antagonizing  teeth  to  the  point  at 
the  cervical  section  showing  the  greatest  recession  or  curve  in  the  gum- 
margin  in  an  apical  direction.  For  a  collar  for  a  root-cap  determine  by 
the  eye,  or  in  a  similar  manner  measure  apically  from  the  surface  of 
the  most  projected  portion  of  the  end  of  the  root  to  the  cervyc.  This 
measurement  is^bestjdone,"  as  shown 
in  the  case  of  a  molar  in  Fig.  231,  with 
a  tapering  strip  of  copper  or  card- 
board with  the  end  squared.  Cut  off 
the  narrow  end  until  it  gages  the 
space.  The  measurement  may  also 
be  taken  with  a  pair  of  dividers. 


Fig.  231. 


Fig.  232. 


Cutting  the  Plate  for  the  Collar.— Place  the  extended  wire  loop  on 
the  surface  of  the  plate  of  which  the  collar  is  to  be  constructed  in  the 
line  of  the  laminae  of  metal,  i.e.,  the  direction  it  has  been  rolled,  and 
mark  the  length.  Next  mark  the  width  by  the  measure  taken,  adding 
one-sixteenth  to  one-eighth  of  an  inch  additional  for  the  free  space 
under  the  gum-margin,  and  any  accidental  discrepancy.  Gage  a  pair 
of  dividers  to  the  mark  and  draw  a  line  on  the  plate,  as  shown  in  Fig. 


Fig.  233. 


Fig.  234. 


232.  Cut  the  plate  along  this  line  to  the  mark  indicating  the  length 
(L,  Fig.  233)  and  about  one-thirty-second  to  one-sixteenth  of  an  inch 
beyond  it  to  allow  an  excess  for  an  overlap. 

When  the  collar  is  to  restore  a  very  large  amount  of  contour 
to  a  bicuspid  or  molar,  the  collar  may  be  cut  across  on  a  slight 
bevel,  flaring  from  the  cervical  to  the  occlusal  edge,  as  shown  in  Fig. 
234.  The  objection  to  a  collar  cut  in  this  form  is  that  as  the  cervical 
edge  is  trimmed,  the  circumference  is  increased  in  size,  a  matter  diffi- 
cult to  calculate  on  by  measurement  in  most  cases. 


GOLD  COLLAR  CROWNS 


149 


Taper  the  edge  of  the  plate  for  theunder-lap  from  the  mark  indicat- 
ing the  length  to  the  edge  of  the  excess,  as  viewed  laterally  enlarged 
at  L,  Fig.  235.  Next  slightly  taper  the  other  end  of  the  plate  for  the 
outer-lap,  as  shown  at  OL;  bend  the  plate  in  a  circle,  and  lap  the  ends 
and  bring  them  in  contact  with  suitable  pliers 
(Fig.  236)  in  the  manner  shown  enlarged  in 
Fig.  237.  Seize  the  collar  at  the  joint  with  a 
clamp  and  hold  it  in  a  Bunsen  flame  until  it 
assumes  a  dull  red,  then  instantly  dip  in  water. 
This  will  cause  the  metal  to  retain  the  curve 
given  it  by  setting  the  molecules  and  will 
permit  the  tapering  edges  of  the  collar  to  be 
brought  together  more   easily.     Repeat  the 


OL 


It 

I'L 


Fig.  235. 


Fig.  236. 


clamping,  annealing  and  chilling  of  the  collar  until  as  perfect  a  contact 

of  the  ends  as  is  possible  is  effected. 

To  Solder  the  Joint  of  the  Collar. — Flux  the  joint;  grasp  the  over-lap 

end  of  the  collar,  as  shown  in  Fig.  238,  and  place  a  minute  piece  of 
^^-  solder  on  the  surface  of  the 

inner  lap  close  to  the  joint 
and  hold  the  collar  in  a 
Bunsen  flame  until  the_solder 
fuses.  The  presence  of  the 
clamp  takes  enough  heat 
from  the  overlap  side  to 
cause  the  solder  to  flow  only 


Fig.   238. 


Fig.  239. 


Pig.  240. 


on  the  inner  lap  side  and  into  the  joint.  The  position  of  the  clamp 
is  then  changed  (Fig.  239),  and  the  solder  flowed  across  the  joint. 
In  this  way  the  particle  of  solder  applied  is  prevented  from  flowing 
on  the  over-lap  instead  of  into  the  joint.  The  smallest  possible  quan- 
tity of  solder  only  is  to  be  applied,  and  it  should  be  as  hard-fusing  as 
the  grade  of  the  gold  of  the  collar  respecting  fusibility  will  permit. 


ISO 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Another  method  is  to  grasp  the  seam  at  the  cervical  side  of  the  collar 
with  the  points  of  a  clamp  or  soldering  pHers  (Fig,  240)  of  the  styles 
illustrated  in  Figs.  241  and  242  and  unite  the  seam  only 
at  the  extreme  outer  edge  with  an  atom  of  solder  fused 
with  a  blowpipe.  The  points  of  the  clamp  or  soldering 
pliers  prevent  the  solder  from  flowing  along  the  joint. 
The  cervical  side  of  the  collar  is  left  open  by  this 
method,  which  permits  the  collar  to  be  slightly  con- 
tracted when  fitted,  if  desired;  after  which  the  solder  is 
flowed  across  the  entire  joint. 

The  collar  when  soldered  is 
slipped  over  the  point  of  a  small 
anvil  and  the  joint  lightly  tapped 
(Fig.  243). 

Sweating  Method. — To  unite 
the  joint  by  the  sweating  method, 
see  Union  by  Sweating,  Part  I, 
Chapter  VI. 

Fitting  a  Collar  to  Root  or 
Tooth. — When  the  collar  seam 
has  been  soldered,  it  is  shaped 
to  the  general  form  (Fig.  244)  of 
the  root  or  tooth  for  which  it  is  in- 
tended, as  illustrated  in  Fig.  245. 
The  collar  is  then  placed  on  the 
root  or  tooth  and  pressed  or,  with 
the  aid  of  a  piece  of  wood  placed 
across  its  outer  edges,  gently 
tapped  up  to  the  margin  of  the 
gum.  A  line  parallel  with  the 
margin  is  marked  with  a  sharp-pointed  instru- 
ment on  the  collar  (A,  Figs.  246  and  247),  which 
is  then  removed,  trimmed  to  this  mark,  re- 
adjusted and  again  marked  (B),  and  the  process 
continued  until  the  collar  fits  correctly  under  the 
gingival  margin,  using  straight  or  curved  small 
pointed  shears  (Fig.  248). 

To  definitely  determine  the  distance  the  edge 
of  a  collar  fits  under  the  gum  margin,  especially  at  the  interproximal 
space,  heat  the  collar,  veneer  its  outer  surface  with  wax,  then  place  a 
small  roll  of  soft  wax  around  the  edge.  Slightly  warm  the  wax  and 
press  the  collar  to  position  and  remove.     The  edge  of  the  gum  will 


Fig.  241. 


Pig.  242. 


GOLD  COLLAR  CROWNS 


151 


press  back  the  wax  and  on  examination  of  the  collar  the  wax  will  ex- 
actly indicate  how  far  the  collar  extends  under  the  gum  (Fig.  249). 

If  the  operation  of  collar  adjustment  is  skilfully  performed  and  the 
collar  is  not  forced  into  the  investing  membrane  of  the  root,  very  little 
pain  will  be  caused  the  patient. 

If,  on  adjusting,  a  collar  is  found  a  trifle  too  small,  it  can  be  slightly 
enlarged  by  tapping  with  a  riveting  hammer  on  an  anvil  the  excess  of 
gold  usually  present  at  the  joint  (Fig.  243).  By  this  means  any  surplus 
gold  at  this  point  in  thrown  into  the  collar  and  its  circumference  pro- 
portionately enlarged  without  materially  altering  its  gage.  If,  on  the 
contrary,  the  collar  should  prove  to  be  too  large  in  circumference,  the 


Fig.  243. 

difiSculty  can  only  be  remedied  by  cutting  the  gold  across  the  [side 
opposite  the  joint,  beveling  and  lapping  the  edges  slightly,  soldering  and 
trimming,  or  by  making  a  new  collar. 

The  collar  having  been  fitted,  the  edge  is  burnished  to  the  periphery 
of  the  root.  For  this  purpose  burnishers  shaped  to  suit  the  different 
positions  and  avoid  irritation  of  the  margin  of  the  gum  should  be  used 
(Fig.  250).  Finely  serrated  foot-shape  gold  foil  condensers  can  be 
advantageously  used  to  flatten  an  edge  of  a  stiff  or  angular  point  of  a 
collar. 

Platinum  Collar, — Platinum  or  iridio-platinum  is  the  ideal  metal 
for  collars  and  is  gradually  being  more  used.  It  withstands  the  action 
of  the  secretions  of  the  mouth  better  than  gold  and  its  presence  is 


152  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

consequently  more  benign  to  the  tissues,  in  which  respect  it  ranks  next 
to  porcelain.  Being  malleable  and  infusible,  it  can  be  easily  and  ac- 
curately adapted. 

Platinum  plate,  gages  Nos.  31  to  32,  is  used  in  the  same  manner  as 
gold,  the  soldering  of  the  joint  and  floors  being  done  with  pure  gold,  or 
with  platinum  solder  when  it  is  to  be  used  for  porcelain  crown- work. 


C3  a 


a         Q 


Q 


Fig.  244. — The  palatal  side  of  the  superior  molars,  in  many  cases,  is  of  the  large 
oval  form  indicated  by  the  outer  line  to  the  form  of  the  first  molar.  The  small 
spurs  indicate  the  points  generally  found  the  most  suitable  to  make  the  joint. 

In  fitting  a  platinum  collar,  the  cervical  portion  may  at  the  same  time 
be  trimmed  to  a  fine  edge  to  facihtate  the  adjustment  under  the  gum- 
margin,  as  there  is  no  danger  of  fusing  the  edge  in  subsequent  soldering. 
Reinforced  Thin  Platinim?  Collar.— This  style  of  collar  is  advan- 
tageous to  use  in  capping  roots  complex  in  form  and  difficult  to  fit,  or 
in  cases  where  the  collar  has  to  extend  far  under  the  gum-margin.     The 


GOLD  COLLAR  CROWNS 


153 


^- 


V 


Fig.  245. 


Pig.  246. 


Pig.  247. 


Fig.  249 


Fig.  250. 


154  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

collar  is  made  of  pure  thin  platinum  plate  about  gage  No.  38.  At  this 
gage  platinum  can  be  easily  fitted  and  accurately  adapted.  The  rein- 
forcement of  the  fitted  collar  is  most  conveniently  done  by  flowing  pure 
gold  over  the  outer  surface.  The  inner  surface;  of  the  collar  is  painted 
with  a  thick  coat  of  rouge.  The  gold  is  cut  in  small  pieces  and  succes- 
sively applied  and  fused  around  the  entire  circumference  of  the  collar. 
If  there  are  any  uneven  places  in  the  surface  of  the  applied  gold,  they 
can  be  trimmed  level  when  the  floor  has  been  attached  to  the  collar. 

Another  method  is  to  fit  the  thin  platinum  collar  to  the  root,  attach 
the  floor  and  then  reinforce  the  collar  by  the  casting  process.  The 
difficulty  encountered  by  this  method  is  that  the  contraction  of  the  gold 
is  liable  to  interfere  with  the  adjustment  of  the  collar  or  cap  on  the  root. 

Platinum-lined  Gold -Plate  Collar. — When  this  form  of  plate  is 
used,  owing  to  the  uneven  expansion  and  contraction  of  the  two  metals, 
the  joint  requires  to  be  securely  clamped  while  being  soldered. 

For  Cast  Gold  Root   Caps  and   Crowns,  see  Part  III,  Chapter  XIV. 

AppUcation  of  a  Local  Anesthetic. — The  application  of  a  local  anes- 
thetic to  the  gingivae  is  suggested  in  fitting  collars.  Adrenalin  and  co- 
cain  are  much  used,  applied  as  described  in  Part  II,  Chapter  III. 
Some  of  the  excess  of  the  application  which  wijl  usually  be  found  at  the 
cervix  may  be  rubbed  on  the  labial  and  lingual  sides  of  the  gum.  A 
little  of  the  solution  may  be  placed  on  the  inner  edge  of  the  collar  before 
it  is  adjusted  on  the  tooth  or  root.  The  patient  should  be  directed  not 
to  swallow  the  saliva  during,  and  for  some  time  after,  the  application  of 
the  cocain.  The  anesthetic  effect  produced  by  this  method  is  of  such 
duration  that  it  will  usually  be  found  sufficient  to  partly  or  entirely 
divest  the  operation  of  pain  and  will  seldom  require  repetition  except 
in  lengthy  operations. 

Collar  Crowns  Hygienically  Considered. — The  principal  argument 
against  collar  crowns  is  that  they  are  productive  of  irritation  to  the  peri- 
dental membrane,  ultimately  causing  its  absorption  and  exposure  of 
the  collar.  This  would  be  theoretically  and  practically  true  of  aiough 
or  porous  substance  encircling  the  root  or  of  an  imperfectly  and  un- 
skilfully adjusted  or  cemented  collar,  which  would  by  its  presence  hold 
a  position  analogous  to  a  calcareous  deposit;  but  it  is  not  fairly  predi- 
cated concerning  a  perfectly  fitted  collar  forming  at  its  edge  a  smooth 
and  imperceptible  union  with  the  sides  of  the  root  and  presenting  a 
uniform  and  benign  surface  to  the  investing  membrane.  The  fact 
should,  however,  be  borne  in  mind,  that  a  collar  of  any  form  is  not 
applied  for  hygienic  purposes,  but  as  a  necessity,  and  at  times  as  an 
unavoidable  adjunct  of  some  restorative  operation. 

In    the  cas*^  of  perfectly  adapted  collars,  when  an  irritation  of  the 


GOLD  COLLAR  CROWNS  155 

membrane  exists,  it  will  usually  be  found  to  result  from  such  causes 
as  produce  it  when  the  natural  crowns  are  presented,  namely,  dental 
concretions.  A  tarnished  and  unclean  condition  of  the  surface  of  the 
gold  of  the  collar  will  produce  irritation  of  the  membranes,  which  is  a 
^matter  independent  of  the  collar  itself  and  easily  remedied  by  cleaning 
and  polishing  the  surface.  Where  an  acid  condition  of  the  secretions 
of  the  mouth  exists,  a  collar  of  platinum  is  suggested  in  preference  to 
gold,  as  this  metal  will  not  be  affected,  but  will  constantly  present  an 
untarnished  surface.  Infection  of  the  cement  under  a  collar  will  cause 
inflammation  of  the  gingival  margin  independent  of  the  collar. 

When  evidence  of  a  tendency  to  pyorrhea  alveolaris  exists,  a  collar 
adjusted  to  support  bridge-work  should  not  be  extended  under  the  gin- 
givae, but  a  space  should  be  left  between  the  edge  and  the  gingivae  so  as 
to  better  permit  treatment  of  the  disease.  When  this  is  not  practical 
the  collar  should  be  made  of  thin  platinum  plate  and  the  edge  closely 
fitted  and  burnished. 


CHAPTER  VIII 

ALL-GOLD  COLLAR  CROWNS  FOR  BlCUSPmS  AND  MOLARS 
CONSTRUCTED  IN  SECTIONS 

METHODS  OF  KNUCKLING  THE  COLLAR  AND  GIVING  CONTOUR — METHODS 
OF  FORMING  THE  CUSP-CAP — CLASS  A,  DIES — METHOD  NO.  I — SWAGING 
THE  CUSP-CAP — STAMPING  THE  CUSP-CAP  IN  A  SWAGER — REINFORCE- 
MENT OF  THE  CUSP-CAP — FITTING  CUSP-CAP  TO  COLLAR — SOLDERING 
CUSP-CAP  TO  COLLAR — SWAGED  CUSP-CAP  — REINFORCED  WITH  2  2- 
CARAT  GOLD — SWEATING — TO  UNITE  BY  SWEATING — METHOD  NO. 
2,  HOLLOW  CUSPS — ^CLASS  B,  INTAGLIO  OR  DEPRESSED  DIES — METHOD 
NO.  3 — METHOD  NO.  4,  CUSP  BUTTONS — APPLICATION — TO  ENLARGE 
A  CUSP  BUTTON — METHOD  NO.  5,  INTAGLIO  DIE  FROM  WAX  MODEL 
— INTAGLIO  DIE-PLATE — CLASS   C,  CASTING — METHOD  NO.  6 — SOLID 

GOLD    CUSP-CAP SPECIAL    METHOD^ — ^METHOD    NO.    7- — SOLID  GOLD 

CUSP-CAP  BY  SOLDERING METHOD  NO.   8 — ^ALL-GOLD  CROWNS   FOR 

— INCISORS   AND   CUSPIDS CASES    OF   ABRASION 

The  root  and  crown  having  been  properly  prepared,  the  collar  is 
formed  and  adjusted  as  described  in  Chapter  VI,  and  the  edge  towards 
the  antagonizing  teeth  trimmed  to  the  line  of  the  points  of  the  cusps  to 
fully  clear  them  in  occlusion  and  provide  space  for  the  placing  of  a  prop- 
erly contoured  cusp-cap.  The  collar  is  then  slightly  expanded  toward 
the  occlusal  surface  for  better  contour  and  the  edge  trimmed  perfectly 
square  and  level  by  rubbing  on  the  flat  surface  of  a  very  fine  file. 

Methods  of  Knuckling  the  Collar  and  Giving  Contour. — If  the 
collar  is  long  enough  a  contour  approximating  that  of  a  natural  tooth 
can  be  imparted  to  the  side  with  the  aid  of  suitable  pliers,  such  as  are 
illustrated  in  Fig.  251,  the  Robinson,  one  beak  of  which  is  rounded  at 
the  point  and  shorter  than  the  other.  The  Peeso  contouring  and  stret- 
ching pliers,  Fig.  252,  and  the  pliers,  Fig.  253,  are  also  useful  for  shaping 
and  removing  inequalities  caused  by  the  use  of  the  first  form.  A  close 
knuckling  can  be  insured  by  pressing  the  collar  against  the  approximal 
teeth  in  the  manner  shown  in  Fig.  254. 

Methods  of  Forming  the  Cusp-cap. — For  the  formation  of  cusp- 
caps  there  are  a  number  of  methods,  of  which  only  those  most  practical 
and  most  used  will  be  presented.     They  will  be  placed  in  three  classes: 

156 


ALL  GOLD  COLLAR  CROWNS  FOR  BICUSPIDS  AND  MOLARS    157 


A,  Stamping  or  swaging  on  the  surface  of  dies;  B,  Shaping  in  intaglio 
or  counter  dies;  and  C,  Casting. 


Fig.  251. 


Fig.  253. 


Fig.  254. 


Fig.  252. 


In  class  A  the  outer  surface  of  the  cusp-cap  is  larger  than  the  die  the 
thickness  of  the  gage  of  gold  plate  used,  and  the  inner  surface  the  exact 
size  of  the  die. 


iss 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


In  Class  B  the  outer  surface  of  the  cusp-cap  is  the  size  of  the  intaglio 
or  depressed  die,  and  its  inner  surface  is  smaller  by  the  thickness  of  the 
gold. 

In  class  C  the  casting  is  an  exact  replica  of  the  wax  model  of  the 
required  cusp-cap. 

Class  A,  Dies 

Method  No.  i.^ — The  superior  molar  to  which  a  collar  has  been  fitted, 
illustrated  in  Fig.  255,  will  be  used  as  a  typical  case.     The  collar  is 


Fig.  255. 


Fig.  256. 


removed  from  the  mouth,  warmed  and  the  inner  surface  veneered 
with  a  film  of  wax  to  facilitate  its  subsequent  removal.  It  is  then 
readjusted  in  the  mouth,  a  wax  ''bite"  taken  and  then  a  compound  or 
plaster  impression  that  will  remove  the  collar  in  position.     (See  Part 


Fig.  257. 


I,  Chapter  IV.)  Next  articulating  models  are  made,  using  a  crown 
articulator,  and  the  models  varnished.  Burnish  layers  of  tin  foil  to 
the  thickness  of  the  gold  plate  that  is  to  form  the  cusp-cap  over  only  the 
surface  of  the  teeth,  or  portions  of  the  teeth,  that  will  antagonize 
the  cusp-cap  as  indicated  in  Fig.  256. 


ALL-GOLD  COLLAR  CROWNS  FOR  BICUSPIDS  AND  MOLARS    1 59 

The  form  of  the  occlusal  surface  of  the  crown  to  be  swaged  is  made 
by  placing  in  the  occlusal  section  of  the  collar  a  ball  of  soft  plaster,  wax 
or  compound  slightly  in  excess  of  what  is  required  for  the  cusp-cap  and 
firmly  occluding  the  models  together,  Fig.  257.  When  the  material 
has  hardened,  open  the  articulator  and  remove  the  surplus  with  a  sharp 
knife.  The  impression  of  the  antagonizing  teeth  will  give  an  outline 
of  the  required  occlusal  surface.     Allowing  for  the  lateral  movements 


Pig.  258. 

of  the  occluding  teeth,  carve  the  cusps,  sulci  and  grooves,  to  as  nearly 
the  natural  form  as  the  circumstances  will  permit.  Typical  forms 
of  occlusal  surfaces  can  be  used  as  a  guide  (Fig.  258).  As  the  gold  cap 
will  strike  up  the  thickness  of  the  plate  larger  and  the  cusps  that  much 
longer,  an  allowance  is  made  for  that  by  the  tin  foil  which  was  placed 
on  the  surfaces  of  the  antagonizing  teeth  when  they  were  occluded  on  the 
plaster  (Fig.  257),  but  the  material  is  to  be  proportionately  removed  at 


i6o 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


the  sides  of  the  collar,  and  its  edge  left  exposed,  as  shown  in  Fig.  259, 
enlarged  in  Fig.  260. 

An  impression  of  the  model  of  the  occlusal  surface  extending  about 
one-sixteenth  of  an  inch  beyond  the  edge  of  the  collar  is  now  taken  in  a 
copper  tube  with  moldine  (Fig.  259).  Paper  is  wound  around  the 
tube  and  a  fusible  metal  die  cast  (Fig.  261).  (See  Figs.  19  and  20, 
Part  I,  Chapter  V.) 


Pig.  259. 

A  counter-die  is  made  by  hammering  the  die  into  a  block  of  lead 
(B,  Fig.  262).  To  slightly  enlarge  the  counter-die  and  make  an  allow- 
ance for  the  gold  plate  before  swaging  and  thus  avoid  the  chance  of 
splitting  it,  cover  the  male  die  with  a  thin  piece  of  kid  and  drive  it  into 
the  counter-die. 

Swaging  the  Cusp-cap. — ^Cut  a  disk  of  the  same  gold  and  gage  as 
the  collar,  in  size  such  as  will  leave  when  swaged  a  surplus  of  about 


d 


Fig.  260. 


Pig.  261. 


Pig.  262. 


one-eighth  of  an  inch  at  the  edge  of  the  cusp-cap;  anneal  the  disk,  oil 
or  vaselin  the  surface  of  the  die  and  counter-die  and  conform  tlie  disk  to 
the  surface  of  the  depressions  of  the  counter-die  with  a  pointed  piece 
of  wood,  by  first  pressing  with  the  point  and  then  tapping  on  the  end 
of  the  wood;  remove  and  anneal  (Fig.  263). 


ALL-GOLD  COLLAR   CROWNS  FOR  BICUSPIDS  AND  MOLARS   l6l 

To  swage  with  the  die  and  counter-die,  place  the  die  (A,  Fig.  264J 
over  the  disk  (B)  and  give  the  die  a  moderately  hard  blow,  driving  it 


Pig.  263. 


Fig.  264. 


Pig.   26.S. 


into  the  counter-die   (C).     Remove  the  disk  and  correct  any  folds 
around  its  margin,  anneal  and.  complete  the  swaging.     Deep  lines  on  the 

die  representing  sulci  can  be  developed 
on  the  gold  with  the  burnisher. 

Stamping  the  Cusp-cap  in  a 
Swager. — In  the  use  of  a  swager,  the 
die  of  the  occlusal  surface  is  cast  in  a 
swager  cup.  The  process  is  as  follows: 
Flatten  out  a  mass  of  moldine,  remove 
the  collar  with  the  form  of  the  occlusal 
surface  from  the  plaster  model  and 
make  an  impression  of  the  occlusal  sur- 
face in  the  center  of  the  moldine.  (See 
Fig.  26,  Part  I,  Chapter  V.)  Adjust  the 
swager  cup  over  the  impression  and  fill 
it  with  fusible  metal  through  the  hole  in 
the  base.  A  cup  with  a  cast  die  in  it 
is  shown  in  section  in  Fig.  265.  The 
disk  of  gold  is  annealed,  placed  in  position  on  the  die,  conformed  to 
its  surface,  removed  and  annealed.  The  gold  is  again  placed  on  the 
die  and  covered  with  a  disk  of  rubber-dam.  The  cavity 
in  the  plunger  is  filled. with  moldine,  the  swager  cup 
inserted  in  the  base  and  the  plunger  hammered  down  on 
the  gold  (Fig.  266),  or  a  soft  rubber  plunger  may  be 
used  instead  of  the  moldine.  Fig.  267  shows  the  inner 
surface  of  the  swaged  cusp-cap. 

Reinforcement  of  the  Cusp-cap. — Paint  the  outer  surface  of  the 
cusp-cap  with  rouge  or  whiting.     First  melt  on  the  corner  of  a  charcoal 
soldering-block  in  the  form  of  a  globule  the  quantity  of  solder — hard 
11 


Pig.  266. 


l62 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


solder  preferred — required  to  fill  the  cusp-cap,  applying  a  moderate 
amount  of  flux.  Next,  place  the  cusp-cap,  occlusal  side  down,  in  the 
middle  of  the  soldering  block,  place  the  globule  of  solder  in  it  and  fuse 
the  globule  into  the  cusps.  This  is  best  done  by  first  uniformly  heating 
both  cusp-cap  and  solder  with  the  large  flame  of  the  blowpipe  to  nearly 
that  of  the  fusing-point  of  the  solder,  a^^d  then  reducing  the  blast  and 
size  of  the  flame  (Fig.  268)  to  a  small  pointed  one  directed  and  steadily 
held  on  the  globule  until  it  gradually  melts  down  and  into  the  cusps  of 
the  cap.  If  necessary  to  heat  up  the  gold  of  the  cusp-cap  during  the 
operation,  or  at  the  finish  to  level  the  surface  of  the  solder  apply  only 
the  large  flame.     Conducted  in  the  manner  described  fusing  of  the 


Fig.  268. 


edge  of  the  gold  of  the  cusp-cap  or  flowing  the  solder  over  the  edge  on 
the  outer  surface  of  the  cap,  which  is  liable  to  occur  if  care  is  not  taken 
and  skill  exercised,  is  avoided.  Next  boil  the  cusp-cap  in  acid  and 
wash. 

Fitting  Cusp-cap  to  Collar. — Cut  a  piece  of  close-grained  pine 
wood  about  six  inches  long,  two  inches  wide  and  one  and  one-fourth 
inches  thick  and  square  and  level  the  end.  Heat  the  cusp-cap  to  a 
dull  red  and  place  and  press  it  occlusal  side  down  into  the  end  of  the 
wood  level  with  the  surface  (Fig.  269).  Thus  embedded,  file  the 
surface  of  the  cusp-cap  and  wood  with  a  coarse  flat  file  until  the  surface 
of  the  cusp-cap  is  uniformly  level.  Finish  with  fine  files.  The  filing 
is  most  conveniently  done  by  fastening  the  wood  in  a  bench  vise,  as 


ALL-GOLD  COLLAR  CROWNS  FOR  BICUSPIDS  AND  MOLARS    1 63 

illustrated   in   miniature  in    Fig.    270.     Remove  the  cusp-cap,  trim 
the  plaster  in  the  collar  level  to  its  occlusal  edge,  fit  the  cusp-cap  to 


Fig.  269. 


Pig.  270. 


collar  and  return  to  wood  block  and  again  file  until  it  fits  perfectly  in 
accordance  with  the  occlusion. 

To  form  a  perfect  and  reliable  joint,  the 
cusp-cap  should  extend  onto  and  slightly- 
over  the  edge  of  the  collar  at  all  points. 
The  edge  of  the  collar  must  be  square  and 
evenly  meet  the  flat  surface  of  the  cusp-cap 
Over  its  entire  circumference;  otherwise,  if 
used  in  bridge-work,  the  joint  is  liable  to 
open  in  soldering  the  bridge. 

Soldering  Cusp -cap  to  Collar. — When 
fitted,  the  cusp-cap  and  collar  are  boiled  in 
acid  and  washed.  The  edges  of  the  collar 
and  the  flat  filed  surface  of  the  edge  of  the 
cusp-cap  are  fluxed,  placed  in  relative  posi- 


PiG.  271. 


tion  and  clamped,  occlusal  side  down,  with  an  adjustable  clamp  (Fig. 
271);  or  wired    together   with   a   piece   of   fine   iron   wire   brought 


l64  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

across  the  cusp-cap  and  the  ends  twisted  together  over  the  edge  of  the 
collar,  as  shown  in  Fig.  272.  Place  around  on  the  inside  of  the  seam 
several  very  small  pieces  of  fluxed  solder,  preferably  the  next  lower- 
fusing  grade  to  that  used  to  fill  the  cusps.  The  crown — occlusal  side 
down,  with  full  view  of  the  inside — is  then  held  in  a  Bunsen  flame  and 
slowly,  uniformly  heated  until  the  solder  fuses  and  flows.  Only 
sufficient  solder  to  properly  unite  the  parts  should  be  used.  If  too 
much  solder  is  applied,  it  is  liable  to  flow  over  the  inner  surface  of  the 
cap  and  on  the  sides  of  the  collar,  or  both,  and  obstruct  the  adjustment 
of  the  crown  on  the  tooth,  a  defect  troublesome  to  correct. 

Swaged  Cusp-cap  Reinforced  with  22-carat  Gold.^^ — Strike  up  the 
cusp-cap  of  pure  or  2  per  cent,  platinized  gold  ^fooo  g^-ge,  which 
doubled  is  about  gage  No.  32.  Plate  of  this  gage  does  not  materially 
affect  the  thickness  of  the  cusp-cap  like  the  use  of  No.  30  gage;  therefore 
very  little  if  any  allowance  is  necessary  in  shaping  the  model  for  the 
cusp-cap.  Fill  in  the  cusp  matrix  with  coin  gold  as  follows:  Scraps  of 
coin  gold  enough  to  fill  the  matrix  are  fused  into  a  globule  as  already 
described;  the  globule  is  placed  in  the  matrix,  occlusal  side  down,  and 
gradually  heated  and  melted  with  a  small  blue  flame  steadily  directed 
on  the  globule  until  it  fuses  and  fills  the  matrix.  No  flux  is  applied. 
Considerable  practice,  as  well  as  care,  is  required  to  successfully  fill 
matrices  of  this  character.  Unite  the  cusp-cap  to  the  collar  from  the 
inside  by  placing  there  a  very  small  quantity  of  solder  and  flux  and 
holding  in  a  Bunsen  flame;  or  use  the  sweating  method. 

Sweating. — When  the  cusjp  matrix  is  filled  in  with  the  same  grade  of 
gold  as  the  collar  and  the  crown  is  to  be  used  as  an  attachment  to  a 
bridge,  this  is  the  preferred  method  of  uniting  cusp-cap  and  collar  by 
many  bridge- work  specialists. 

To  Unite  by  Sweating. — The  edge  of  the  collar  and  surface  of  the 
cap  must  meet  at  every  point.  The  collar  and  cusp-cap  having  been 
boiled  in  acid  are  fluxed  and  clamped  or  wired  together  (Figs,  271  and 
272),  and  held  cusps  down  in  a  Bunsen  flame  so  that  the  thick  cusp-cap 
will  be  heated  first.  They  are  kept  there  until  nearly  at  the  fusing 
point.  The  entire  crown  is  then  lowered  a  little  in  the  flame  and  held 
until  the  gold  begins  to  melt  and  unites  collar  and  cusp-cap,  when 
they  are  instantly  removed.  This  method  requires  practice.  It  should 
be  first  studied  before  trying  it  on  a  practical  case.  (See  Part  I, 
Chapter  VI.) 

Method  No.  2,  Hollow  Cusps. — This  form  of  a  cusp-cap  is  for  use 
when  a  sound  or  only  slightly  decayed  bicuspid  or  molar  is  to  be  capped 

1  This  method  of  forming  a  cusp-cap  and  then  sweating  it  to  the  collar  is  that 
practiced  and  taught  by  Dr.  Peeso. 


ALL-GOLD  COLLAR  CROWNS  FOR  BICUSPIDS  AND  MOLARS    165 


Fig.  273. 


with  gold,  for  instance,  as  an  abutment  for  a  bridge,  and  on  account  of 
shortness  of  crown  or  some  other  reason,  removal  of  the  least  possible 
portion  of  the  occlusal  surface  is  desired.  The  inner  surface  of  the  cap 
in  such  a  case  must  necessarily  conform  more  or  less  to  the  occlusal 
section  of  the  tooth.  If  antagonizing  teeth  are  present,  enough  sub- 
stance must  be  removed  from  the  occluding  teeth  or  the  one  capped,  or 
both,  to  allow  for  the  intervening  thickness  of  the  plate  forming  the 
cusp-cap.  In  such  a  case  fit  the  collar  and  trim  enough  off  the  occlusal 
edge  of  the  collar  to  leave  the  cusps  of  the  tooth  exposed.  Press  a 
ball  of  softened  impression  compound  over  the  occlusal 
surface  and  the  edge  of  the  collar,  allow  it  to  cool  and 
then  remove  the  collar  and  compound  together.  Fill  the 
impression  inside  the  collar  with  plaster  and  when  the 
plaster  has  set  remove  the  compound.  This  gives  a 
plaster  model  of  the  occlusal  surface  within  the  collar 
as  in  the  mouth,  as  outlined  in  Fig.  273. 

Take  an  impression  or  mold,  make  die  and  strike  up  a  cap  of  gage 
No.  28  to  30,  the  same  as  in  Method  No.  i.  Leave  a  slight  overlap 
edge  to  the  cap  as  it  meets  the  outer  edge  of  the  collar.  Remove  the 
plaster  from  the  inside  of  the  collar  and  attach  the  cusp-cap  to  the 
collar  on  the  outside  with  wax,  flowing  the  wax  over  and 
/A  into  the  seam.  Fill  the  inside  of  the  collar  and  cap  with 
\  /  /  j  investment  material  and  wire  or  clamp  the  cap  and  collar. 
Heat  the  investment  slowly  so  as  to  burn  off  the  wax  and 
not  displace  the  cap  with  steam  from  the  investment. 
Holding  cap  and  collar  in  position,  unite  them  from  the 
outside  by  flowing  the  least  possible  quantity  of  solder  in 
the  seam.  The  slightly  projecting  edge  of  the  cusp-cap 
will  retain  the  solder,  which  should  be  applied  in'  very 
small  pieces  in  position. 

A  variation  of  this  method  is  to  mark  the  outline  of  the  occlusal 
surface  on  the  inner  surface  of  the  collar,  then  remove  the  collar  and 
trim  so  as  to  leave  a  border  of  about  one-sixteenth  of  an  inch  outside 
the  mark.  This  border  is  then  thinned  with 
a  carborundum  wheel,  and  slit,  as  seen  in  Fig. 
274.  The  collar  is  next  adjusted  on  the  natural 
crown  and  the  slit  border  bent  over  to  the  form 
of  the  occlusal  surface,  to  which  it  is  burnished. 
A  cusp-cap  stamped  with  a  die  of  the  occlusal 
surface  or  one  closely  approximating  it  is  then 
adjusted  on  the  collar  in  the  mouth,  the  occlusion  of  the  cusp-cap 
tested  by  occluding  the  teeth,  and  the  cusp-cap  and  collar  removed. 


Pig.  274. 


Pig.  275. 


i66 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


They  are  then  clamped,  as  shown  in  Fig.  275,  and  the  cusp-cap 
fastened  only  at  the  point  A  with  an  atom  of  solder.  The  crown  is 
then  readjusted  on  the  tooth  and  the  edges  of  cap  and  collar  brought 
together  with  a  foot-shape  foil  condenser,  also  by  occluding  the  teeth, 
if  any  are  present,  and  the  soldering  completed  by  degrees.  In  such 
cases  as  described,  if  the  antagonizing  teeth  are  present,  the  cusp- 
cap  is  preferably  made  of  platinized  gold  (clasp  gold)  to  better  resist 
the  wear  of  mastication. 

Class  B,  Intaglio  or  Depressed  Dies 

Method  No.  3. — Form  on   the  collar  the  required  cusp-cap  in 
plaster  or  metalline^  and  embed  the  collar — cervical  end  down — in  a 
flattened  lump  of  moldine  ex- 
actly to  the  line  of  junction  of 


Fig.  276. 

the  gold  collar  and  cusp-cap 
model  (Fig.  276).  Place  the 
swaging  cup  of  the  swager  over 
it  and  pour  in  fusible  metal. 
When  chilled,  remove  crown 
and   moldine   and  vaselin  the 


Pig.  278. 


Pig.  277. — PM,  Fusible  Metal. 


surface  of  the  die,  then  start  the  gold  plate  into  the  depressions  with 
the  point  of  a  piece  of  wood  by  tapping  on  the  end.  Remove,  anneal 
and  replace  the  gold,  insert  the  cup  in  swager  and  complete  the  swag- 
ing with  the  plunger  (Fig.  277). 

Method  No.  4,  Cusp-buttons. — This  consists  in  the  use  of  solid 
metallic  models  of  the  occlusal  surfaces  of  bicuspids  and  molars  to  form 
intaglio  cusp-cap  dies  for  crowns  or  dummies  (Fig.  278). 

1  A  mixture  of  carbon  and  impression  compound  sold  for  such  purposes. 


ALL-GOLD  COLLAR  CROWNS  FOR  BICUSPIDS  AND  MOLARS     167 

Cusp-buttons  are  made  by  stamping  sheet  copper,  gage  No.  36, 
to  the  form  of  an  occlusal  surface  and  filling  the  matrix  with  lead  or 
tin  by  fusing  it  in  a  Bunsen  flame,  using  zinc  chlorid  as  a  flux.  The 
surface  is  then  filed  perfectly  level  by  rubbing  on  the  surface  of  a  fat 
file.  The  buttons  should  be  arranged  in  sets  so  that  the  required  form 
or  size  can  be  easily  selected  as  shown  in  Fig.  279. 

Application. — Fit  the  collar  and  select  a  cusp-button.  Remove 
enough  of  the  occlusal  edge  of  the  collar  to  make  room  for  the  cusp- 
button  and  file  the  edge  of  the  collar  perfectly  level.  Place  a  little 
wax  inside  the  collar  to  assist  in  retaining  the  cusp-button  in  position. 


Pig.  279. 

The  cusp-button  selected  should  be  fully  as  large  as  the  circumference 
of  the  collar,  should  articulate  properly  and  correspond  in  shape  with 
the  other  teeth.  Remove  the  button  and  place  it  on  a  level  cake  of 
moldine — occlusal  side  up, — cover  it  with  a  swager  cup  and  flow  in 
fusible  metal  (Fig.  280).  When  cool,  remove  cusp-button,  place  the 
gold  plate  over  the  intaglio  or  depressed-die  and  swage  the  gold  into  the 
die  with  the  plunger.  This  gives  a  cusp-cap  of  the  exact  form  and  size 
of  the  cusp-button  the  gage  of  the  plate  smaller  on  its  cavo-surface. 
If  among  the  cusp-buttons  on  hand  none  articulates  perfectly, 
the  difficulty  is  usually  remedied.by  taking  the  button  which  most 


i68 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


nearly  answers  and  building  up  the  cusp  with  moldine  (Fig,  281). 
If  a  collar  is  accidentally  cut  too  short,  it  may  in  some  cases  still 
be  utilized.     Place  moldine  upon  the  molding  plate,  set  and  adjust 


Fig.  280. 


Pig.  281. 


Pig.  282. 


the  cusp-button  upon  it,  press  and  cut  away  the  moldine  enough  to 
make  up  the  deficiency  of  the  collar  (Fig.  282).  This  will,  of  course, 
throw  the  soldering  line  a  little  farther  up  the  crown. 


M_ 


0Kf-    dtnf-    ^KW^    it^   -4k 


Pig.  283. 

To  Enlarge  a  Cusp  Button. — To  make  a  cusp-cap  the  thickness  of 
the  gold  plate  larger,  fill  the  swager  cup  with  impression  compound 
and  level  the  surface.  Lay  the  cusp  button — occlusal  surface  upward — 
on  the  center.     Place  and  swage  the  gold  plate  over  the  cusp  button. 


ALL-GOLD  COLLAR  CROWNS  FOR  BICUSPIDS  AND  MOLARS    169 

Method  No.  5,  Intaglio  Die  from  Wax  Model.-  Shape  the  model 
of  the  occlusal  surface  on  the  collar  with  stiff  plate- wax.  Fill  a  swager 
cup  with  impression  compound  and  level  and  warm  the  surface  so  that 
it  is  quite  soft.  Oil  the  wax  model  lightly;  chill  with  cold  or  ice-water, 
press  into  the  surface  of  the  warm  compound  to  the  line  of  the  occlusal 
edge  of  the  collar  and  immediately  chill  the  compound  by  immersing 
in  or  placing  under  running  water.  If  properly  done  the  heat  of  the  com- 
pound will  not  at  all  disturb  the  wax  form.  Remove  the  wax  model. 
This  gives  an  intaglio  die  of  impression  compound  into  which  can  easily 
be  swaged  pure  gold,  gage  No.  38,  and  even  22-carat  gold  by  frequent 
annealing. 

Paint  the  outer  edge  of  the  swaged  gold  form  of  the  cusp-cap  with 
rouge,  place  it  on  a  soldering  block  and  with  a  blowpipe  melt  into  it 
globules  of  coin  gold  or  hard  solder  until  it  is  full.  A  satisfactory 
cusp-cap  is  quickly  made  by  this  method. 

Intaglio  Die-Plate. — Intaglio  die-plates  (Fig.  283)  of  the  occlusal 
surfaces  of  bicuspids  and  molars  are  manufactured  and  sold  for  use  in 
forming  cusp-caps.  They  are  not  as  convenient  to  use  as  the  cusp- 
button  method,  as  the  latter  permits  the  required  form  and  size  to  be 
more  easily  determined. 

Class  C,  Casting 

Method  No.  6.  Solid  Gold  Cusp-cap. — Casting  is  the  preferred 
method  for  cusp-caps.     Form  on  the  collar  a  model  of  the  required 
cusp-cap  with  inlay  wax,  with  the  collar  in  position  or 
mounted  on  a  model,  as  described  in  Method  No.  i, 
using  wax  instead  of  plaster.     Have  the  inner  edge  of 
the  collar  slightly  embedded  in  the  wax.     Chill  and  re- 
move the  wax  cusp-cap  model,  invest  and  cast.     The 
sprue  is  inserted  in  the  thickest  part  of  the  wax  before  or 
after  its  removal  from  the  collar,  as  shown  in  Fig.  45 
(Part  I,  Chapter  VII).     The  wax  model  of  the  cusp- 
cap  may  be  invested  in  position  on  the  collar  and  cast 
directly  on  it.     In  such  a  case  wax  not  necessary  to  the 
cusp-cap  should  be  removed  from  the  inner  surface  of  the  collar  to  in- 
sure easy  adjustment  of  the  finished  crown. 

This  method  is  further  varied  by  capping  the  occlusal  end  of  the 
collar  with  a  floor  of  thin  gold  plate  or  i/iooo  platinum  (A,  Fig.  284) 
and  shaping  the  wax  model  of  the  cusp-cap  on  it.  When  the  cusp-cap 
is  cast  (B)  clamp  and  solder  it  on  the  floor  of  the  collar. 


17©  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Special  Method 

Method  No.  7»  Solid  Cusp-cap  by  Soldering. — When  intervening 
space  will  permit  the  formation  of  a  soHd  gold  occlusal  surface  to  a  col- 
lar crown  the  following  is  a  practical  method:  Fit  the  collar  and  trim 
the  edge  toward  the  occlusal  surface  so  as  to  leave  between  it  and  the 
cusps  of  the  occluding  teeth  a  space  of  at  least  one-sixteenth  of  an  inch. 
Remove  the  collar  and  cap  the  occlusal  surface  with  a  floor  of  gold  plate 
about  gage  No.  30,  using  a  very  small  quantity  of  hard  solder  to  unite 
it  to  the  collar.     Trim  off  the  surplus  plate  flush  with  the  collar. 

To  form  the  cusps,  melt  scraps  of  gold  plate  on  the  surface  of  a 
soldering-block  into  small  globules,  one  for  each  cusp,  and  slightly 
flatten  each  globule  on  an  anvil  with  a  hammer.  Place  the  globules  on 
the  surface  of  the  cap  in  proper  position  to  form  the  cusps  and  attach 
each  with  a  small  piece  of  hard-flowing  solder  (Fig,  285).     When  all 


o!eB 


Pig,  285.  Pig.  286. 

the  cusps  are  attached,  add  sufficient  ordinary  solder  to  properly  fill  in 
and  give  form  to  the  surface  of  the  cap.  Adjust  the  cap  in  the  mouth 
and  trim  the  gold  of  the  occlusal  surface  to  the  form  that  will  suit  the 
occlusion,  then  polish  the  crown.  This  is  a  very  practical  and 
quick  method  of  forming  a  gold  crown,  especially  in  a  case  of 
mechanical  abrasion  and  short  cusps. 

Method  No.  8. — -When  the  mere  form  of  the  occlusal  surface  for  the 
crown  is  all  that  is  required,  as  in  cases  of  mechanical  abrasion,  or  for  a 
temporary  crown,  an  impromptu  one  may  be  made  by  indenting  a 
piece  of  pure  or  soft  gold  plate  with  the  round  end  of  an  instrument  han- 
dle on  a  piece  of  lead  to  form  the  cusps,  then  reverse  the  cap,  resting 
it  on  a  flat  surface,  and  creasing  between  the  cusps  with  a  burnisher. 
One  large  indentation,  such  as  is  shown  at  A,  Fig.  286,  which  when 
indented  and  creased  across  the  center  with  the  edge  of  a  flat  thin 


ALL-GOLD  COLLAR  CROWNS  FOR  BICUSPIDS  AND  MOLARS    171 

burnisher  will  represent  a  bicuspid;  four  indentations  closely  made,  as 
shown  at  B,  when  creased  between,  can  be  used  to  represent  an  upper 
or  lower  molar,  and  three  similar  indentations,  properly  creased,  a 
second  or  third  upper  molar,  as  seen  at  C. 


Fig.  287. 

All-Gold  Crowns  for  Incisors  and  Cuspids 

When  the  teeth  are  abraded  and  short,  with  flat  incisal  edges  or 
occlusal  surfaces  (Fig.  287),  and  the  all-gold  crown  required  is  to  cor- 
respond in  form  and  be  only  a  little  longer,  the  tooth  is  first  trimmed  and 


properly  shaped.  The  gold  collar,  after  being  fitted  to  the  cervical 
section,  is  slit  on  the  lingual  side  and  bent  and  burnished  against  the 
tooth.  The  collar  is  then  removed  and  the  seams  soldered  together. 
This  is  best  done  by  holding  the  collar  in  a  Bunsen  gas  flame  with  the 
solder  placed  in  position  in  very  small  pieces  and  only  sufficient  in 
quantity  to  join  the  seams.     The  collar  is  next  adjusted  to  the  tooth 


172  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

and  the  gold  at  the  incisal  edge  trimmed  even.  A  flat  thick  piece  of 
gold  plate  or  clasp  gold,  as  heavy  as  22  gage  or  No.  30  gage  additionally 
reinforced,  is  soldered  across  the  incisal  edge  to  form  and  inclose  that 
portion  of  the  crown. 

Cases  of  Abrasion. — Fig.  287  represents  a  case  of  abrasion  of  the 
lower  teeth  to  which  all-gold  crowns  were  applied  to  open  the  "bite," 
as  shown  in  Fig.  288.  In  such  cases,  owing  to  the  attrition  of  the  oc- 
cluding teeth,  the  cap  formmg  the  occlusal  surface  should  invariably 
be  constructed  of  heavy  gold  clasp  plate  of  one  or  several  layers  and 
solder  as  the  case  permits  or  suggests.  One  or  two  holes  punched 
through  each  piece  as  it  is  applied  facilitates  their  union  with  the  solder. 
An  artificial  plate  replaced  the  upper  teeth  in  the  case  illustrated. 

In  a  case  such  as  this  the  patient  is  usually  advanced  in  years.  In 
their  treatment  the  opinion  of  most  practitioners  is,  that  only  a  partial 
restoration  of  the  teeth  in  length  is  advisable.  An  operation  for  a 
young  patient  would  be  under  different  conditions  and  would  not  be 
included  in  this  opinion.  In  persons  of  advanced  years  the  sockets 
of  teeth  artificially  lengthened  do  not  always  readily  accept  the  sudden 
change  respecting  leverage  and  force  of  occlusion. 

a        To  gage  the  space  to  open  the  ''bite,"  the  best  method 
is  to  first  crown  a  tooth  on  the  right  or  left  side  or  on  both 
sides  with  an  extra  thick  occlusal  surface,  then  insert  and  trim 
to  the  length  required,  which  will  furnish  the  proper  gage  for 
the  others. 
Gold  crowns  to  be  given  a  normal  form  require  the  fitted  collar  to 
be  cut  away  at  the  lingual  section,  as  shown  in  Fig.  289.     The  edge  of 
the  gold  is  then  chamfered,  bent  and  burnished  over  the  incisal  edge 
and  sides  close  to  the  natural  tooth.     To  this  open  section  is  next 
adapted  a  curved  piece  of  gold  plate,  the  collar  is  removed  and  the 
parts  are  soldered  together,  using  only  a  small  quantity  of  hard  solder. 
Small  pieces  of  ordinary  solder  or  solder  filings  can  be  melted  in  the 
interior  of  the  incisal  edge  to  resist  attrition.     A  fusible  metal  die  of  the 
prepared  form  of  the  natural  tooth  is  a  material  aid  in  the  construction 
of  any  of  these  styles  of  crowns. 

In  pulpless  teeth  with  only  a  little  or  none  of  the  natural  crown 
remaining,  the  root  can  be  shaped  and  capped  the  same  as  for  a  collar 
crown  with  a  porcelain  facing,  with  a  post  in  the  root-canal.  A  gold 
facing  is  then  applied  instead  of  one  of  porcelain.  This  is  done  by 
shaping  or  stamping  the  form  of  the  labial  face  of  the  tooth  required  in 
gold  plate,  filling  it  with  hard  solder,  mounting  it  in  position  on  the  cap, 
as  in  the  case  of  a  porcelain  facing,  and  attaching  and  giving  any  neces- 
sary shape  to  the  lingual  side  with  ordinary  solder. 


ALL-GOLD  COLLAR  CROWNS  FOR  BICUSPIDS  AND  MOLARS    173 

To  make  an  intaglio  die  to  shape  a  gold  facing,  select  a  suitable 
sized  porcelain  tooth,  place  it  face  upward  on  a  flat  piece  of  moldine, 
place  the  swager  cup  over  it  and  cast  in  fusible  metal.  (See  Part  I, 
Chapter  V.) 

The  construction  of  an  all-gold  cap-crown  for  an  incisor  or  cuspid 
is  most  easily  accomplished  by  the  seamless  method  described  in  Chap- 
ter XI. 


CHAPTER  IX 
GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS 

INCISORS  AND  CUSPIDS — ADAPTATION  OF  THE  COLLAR — TO  FORM  FLOOR 
OF  THE  COLLAR — -INDIRECT  METHOD — ^PREPARATION  OF  CANAL  TO 
RECEIVE  POST — ^POSTS — UNION  OF  POST  AND  CAP — SELECTION  AND 
ADAPTATION  OF  THE  PORCELAIN  FACING — TO  PROTECT  THE  INCISAL 
EDGE  OF  THE  PORCELAIN  FACING — ^BACKING  THE  PORCELAIN  FACING 

ONE-PIECE    BACKING — ^POINTED-PIN   FACINGS — USE     OF    SWAGER 

PREPARATION   FOR   INVESTMENT — ^INVESTMENT— SOLDERING  AND 

FINISHING — -DIVERSITY  OF  CONSTRUCTION — METHOD  OF  FORMING 
POSTS  TO  ACCURATELY  FIT  CANALS — ^HOLLOW  POSTS — ^CONSTRUC- 
TION— TO  SEPARATELY  BACK  OR  VENEER  THE  BASE  OF  A  PORCELAIN 

FACING       WITH       PLATINUM TWO-PIECE       BACKING — REINFORCED 

BACKING 

This  style  of  crown,  for  incisors  and  cuspids,  as  originally  made  by 
Dr.  C.  M.  Richmond  and  with  which  his  name  is  commonly  associated, 
originally  consisted  of  a  cap  for  the  root  formed  of  a  band  of  gold  with  a 
platinum  floor  on  which  was  soldered  a  tooth  with  a  slot  in  the  center 
between  the  pins.  Through  this  slot  and  the  center  of  the  cap  a  screw 
passed,  which  entered  into  a  cylinder  previously  screwed  and  cemented 
into  the  root-canal. 

The  form  of  gold  collar  crown  with  porcelain  facing  now  in  general 
use  is  in  principle  the  same  as  what  was  formerly  known  in  dentistry 
as  a  gold  pivot  tooth,  with  the  addition  of  a  gold  collar  for  the  root  and 
having  the  advantage  of  zinc-oxyphosphate  for  its  cementation.  These 
improvements  enhance  its  value  as  a  crown  and  materially  changfe  the 
process  of  its  construction. 

Incisors  and  Cuspids 

Adaptation  of  the  Collar. — In  making  an  incisor  or  cuspid  crown 
of  this  style  the  root-canal  is  treated,  the  root  shaped  and  a  collar  made 
and  fitted,  as  described  in  the  preceding  chapters.  The  collar  is  held 
in  position  on  the  root,  a  sharp-pointed  instrument  introduced  inside 
the  collar,  and  the  line  of  the  surface  of  the  root  scratched  on  the  metal 
around  the  circumference.  The  collar  is  removed  and  trimmed  a  trifle 
flush  to  this  mark  with  small  pointed  shears.     It  is  then  adjusted  on  the 

174 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS  175 

root  and  the  edge  of  root  and  collar  ground  even,  removing  some  of  the 
surface  of  the  root  if  necessary  for  this  purpose.  In  the  operation  of 
grinding,  the  collar  should  first  be  firmly  held  in  position  on  the  root 
at  the  labial  side  while  the  lingual  section  is  ground,  then  at  the  lingual 
while  the  labial  is  being  reduced.  At  the  labial  section,  the  collar 
and  surface  of  the  root  should  be  removed  so  as  to  be  invisible  if  the 
patient  exposes  the  gum-margin  in  speaking  or  laughing.  To  positively 
insure  such  a  result  in  the  finished  crown,  it  is  advisable  to  first  grind 
and  shape  the  end  of  the  root  and  the  base  of  the  porcelain  facing,  the 
one  to  the  other,  with  the  collar  removed,  making  an  allowance  for 
the  thickness  of  the  floor  of  the  cap.  In  cases  where  there  is  no  exposure 
of  the  gum-margin  in  the  movement  of  the  lips,  a  proportionate  amount 
more  of  the  collar  and  root  may  remain.  This  is  often  desirable,  as  it 
affords  additional  strength,  especially  when  the  crown  is  to  be  used  as 


Fig.  290.  Fig.  291.  Fig.  292. 

an  abutment  in  bridge-work.  The  work  then  will  present  the  appear- 
ance about  the  collar  shown  in  Figs.  290  and  291. 

As  the  sides  of  the  collar  are  parallel  with  the  line  of  the  cervical 
section  of  the  root,  the  edge  of  the  collar  at  the  lingual  side  forms  an 
angle  with  the  surface  of  the  end  of  the  root  (A,  Fig.  290).  In  close 
occlusions  this  is  liable  to  give  a  conformation  to  the  finished  crown 
at  that  point  quite  perceptible  and  objectionable  to  the  patient. 
This  can  be  avoided  by  slightly  rounding  off  the  lingual  side  of  the  root 
to  the  form  illustrated  at  B,  Fig,  291.  The  collar  is  then  slit  two-thirds 
across,  as  outlined  at  S,  the  edges  beveled  slightly,  lapped,  fitted  on 
the  root,  pressed  and  burnished  to  form  and  soldered.  In  the  finished 
crown  the  collar  will  then  present  a  form  nearer  that  of  the  natural 
tooth,  as  illustrated  in  Fig.  292. 

To  Form  the  Floor  of  the  Collar. — The  floor  of  the  collar  that  com- 
pletes the  cap  is  made  of  gold  gage  No.  30  or  thin  platinum  plate  gage 
No.  38  to  40.     Thin  platinum  plate  or  3^1000  platinum  foil  is  preferable 


176  CROWN;  BRIDGE-,  AND  PORCELAIN-WORK 

when  it  is  desirable  to  have  the  least  possible  space  occupied  by  the  floor 
at  the  labial  section.  The  thinness  of  the  platinum  forming  the  floor 
to  the  cap  does  not  materially  affect  the  strength  of  the  finished  crown, 
as  that  part  is  reinforced  by  the  solder  subsequently  applied.  When 
the  cap  is  for  a  removable  tube  and  split-post  crown,  the  floor  is  to  be 
made  of  the  same  grade  of  plate  as  the  collar,  gage  No.  28. 

A  piece  of  the  gold  or  platinum  plate  is  cut — square  or  round — con- 
siderably larger  than  the  circumference  of  the  collar.  The  outer  edge 
of  the  collar  having  been  filed  level  is  placed  against  the  floor  and 
adapted  to  its  surface  by  slight  pressure  between  the  fingers.  With 
the  collar  resting  on  the  floor,  the  edge  is  seized  with  a  clamp,  a  piece 
of  solder  with  flux  is  placed  on  the  gold  or  platinum  outside  of  the  collar, 
as  shown  in  Fig.  293.  The  whole  is  then  held  in  the  flame  of  a  Bunsen 
burner,  the  solder  fused  and  collar  and  floor  united.  The  quantity  of 
solder  applied  must  be  very  small,  barely  sufficient  to  unite  the  parts,  so 
that  it  shaU  not  flow  over  the  inside  of  the  cap  and  interfere  with  its 
.  fit  on  the  root.     All  parts  of  the  edge  of  the 

^^^pl       collar  should  touch  the  floor  before  they  are 
^^     \     soldered;  otherwise,  in  subsequent  soldering, 
WMlif         the   seam  is  liable  to  open.     Perfection  in 
\  \ 111        ^^^^  P^^*'  ^^  ^^^  work  is  most  easily  attained 
lilil        ^y  ^^^^  attaching  the  gold  or  platinum  to 
WmM        the  edge  of  the  collar  at  one  point  with  a 
in        mere  particle  of  solder  to  retain  and  hold  it 
in   position,   and    then   readapting    the   re- 
mainder  of   the   edge   and   completing    the 
soldering. 

The  position  of  the  tweezers  should  be  changed  during  the  soldering, 
as  they  conduct  the  heat  from  the  metal  at  the  point  held.  When  the 
collar  and  floor  are  united,  the  plate  is  trimmed  flush  with  the  outline 
of  the  collar  with  small  shears  and  finished  smooth  with  a  carborundum 
point.  At  the  cervical  edge,  in  some  cases,  it  is  well  to  have  the  floor 
extend  slightly  beyond  the  collar  so  as  to  accommodate  proper  align- 
ment of  the  facing  in  a  labial  direction  and  to  assist  in  shaping  the  collar 
with  solder  at  that  point  later  on. 

The  cap  is  next  adjusted  on  the  root.  Should  any  part  of  the  cap 
not  seem  to  fit  in  position  accurately,  a  foot-shape  foil  condenser 
pressed  or  malleted  along  the  edge  of  the  collar  at  the  part  soldered  to 
the  floor  will  correct  it,  if  the  soldering  has  been  properly  conducted. 
Pressure  is  next  exerted  with  the  finger  on  the  palatal  side  of  the  cap  to 
retain  it  in  position  while  the  labial  section  of  both  floor  and  collar  is 
burnished  to  the  root.  This  adaptation  steadies  the  cap  on  the  root. 
The  cap  is  then  ready  to  receive  the  post. 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS 


177 


Indirect  Method. — If  this  method  is  pracliced  in  forming  a  collar  and 
floor  on  a  die  (Part  I,  Chapter  V),  swaging  should  be  omitted,  as  it 
distorts  the  position  of  the  collar.  Swaging  is  best  applied  to  seamless 
root-caps,  (Formation  of  Cast  Root-Caps  is  described  in  Part  III, 
Chapter  XIII.) 

Preparation  of  Canal  to  Receive  Post. — In  a  collar  crown  of  the 
style  described,  the  collar  is  largely  relied  upon  for  retention  on  the  root, 
and  the  post  is  therefore  not  usually  so  important  a  part  as  in  a  crown 
where  a  partial  collar  or  no  collar  is  used.  To  receive  the  post,  the  root- 
canal  is  first  opened  up  with  Gates-Glidden  drills  and  then  with  suitable 
reamers  enlarged  to  the  size  of  the  intended  post  (B,  Fig.  294).  The 
orifice  of  the  canal  should  be  countersunk  a  little  with  a  large  round  bur 
to  give  it  a  slightly  cup-shape  form.  Into  this  depression  the  gold  or 
platinum  of  the  floor  of  the  collar  can  be  burnished  with  a  cone-pointed 
burnisher.  The  object  of  the  depression  is  to  provide  a  space  to  flow 
the  solder  m  aiound  the  post  to  reliably  attach  it  to  the  floor,  especially 


Pig.  295. 


Pig.  296. 


should  conditions  require  that  the  end  of  the  post  be  ground  off  close  to 
the  surface  of  the  floor  (Fig.  295,  in  section). 

Post. — Gold  clasp  or  iridio-platinum  wire,  preferably  round,  gage 
No.  14  to  18 — a  little  smaller  for  laterals  or  other  roots  which  require 
its  reduction — is  used  for  posts. 

The  use  of  posts  made  of  alloys  of  the  base  metals  is  to  be  con- 
demned for  this  style  of  work.  The  wire  for  the  posts  may  first  be 
rolled  under  a  flat  file  to  roughen  its  surface.  It  should  be  slightly 
rounded  or  tapered  at  the  point  and  introduced  one  quarter  of  an  inch, 
more  or  less,  up  the  canal,  as  indicated  by  the  conditions  of  the  case 
respecting  length  of  root,  size  of  artificial  crown  to  be  mounted  and 
character  of  the  occlusion  (Figs.  294  and  296).  A  large,  long  crown, 
or  a  close  occlusion,  suggests  a  longer  and  heavier  post  than  a  small  or 
short  crown  or  a  more  favorable  occlusion.  If  the  canal  is  for  any 
reason  much  enlarged,  the  point  of  the  post  should  be  tapered  and 
extended  to  its  extremity  in  order  to  strengthen  the  root  as  well  as 
anchor  the  crown.  When  gutta-percha  is  used  to  attach  the  crown,  a 
12 


178  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

longer  post  is  required  than  for  zinc  oxyphosphate,  and  the  post  should 
fit  the  canal  in  such  a  manner  as  to  require  the  presence  of  only  a  very 
small  quantity  of  gutta-percha  to  secure  it  (Figs.  296  and  298). 

Union  of  Post  and  Cap. — -The  post  having  been  fitted,  the  cap  is  'ad- 
justed on  the  root,  the  floor  over  the  canal  is  burnished  into  the  orifice 
and  punctured.  The  end  of  the  post  is  seized  with  wire  pliers  and  the 
point  inserted  and  forced  through  the  puncture  in  the  floor  to  position 
in  the  canal,  and  the  correctness  of  its  relations  with  the  cap  observed 
and  decided.  Cap  and  post  are  next  removed,  dried,  slightly  heated, 
and  the  surface  of  the  floor  and  exposed  end  of  the  post  veneered  with 
adhesive  wax.  The  cap  and  post  are  again  adjusted  to  position  on  the 
root,  protected  from  moisture,  and  a  small  pellet  of  slightly  heated 
wax  is  placed  over  the  end  of  the  post  and  pressed  against  the  surface 
of  the  cap  and  around  the  post.  The  wax  is  chilled  with  water  and  the 
cap  and  post  carefully  removed  and  invested.  The  investment  ma- 
terial should  be  run  into  the  interior  of  the  cap  so  as  to  fill  every  crevice. 
When  set,  the  wax  is  removed  by  pouring  on  boiling  water  and  the 
investment  is  trimmed  and  reduced  to  as  small  a  size  as 
permissible  (Fig.  297).  It  is  next  heated  and  solder  flowed 
into  the  depression  around  the  post  flush  with  the  surface 
p  of  the  cap,  also  over  the  surface  of  the  floor  at  the  lingual 
Fig  207  ^^^^'  ^^  made  of  thin  platinum.  Should  any  extensive 
aperture  exist  in  the  gold  or  platinum  around  the  post  at 
the  orifice  of  the  canal  before  soldering,  a  pellet  of  Corona  gold  may 
be  gently  pressed  in  the  place  to  aid  the  solder  in  filling  it  up.  After 
removal  from  the  investment  and  boiling  in  acid,  the  cap  and  post  are 
adjusted  in  position  on  the  root.  'p> 

Selection  and  Adaptation  of  the  Porcelain  F^ing. — The  adaptation 
of  the  porcelain  facing  to  the  cap  is  next  made,  either  directly  in  the 
mouth,  or  by  the  aid  of  a  model  of  the  case.  When  a  model — which 
is  the  best  method — is  to  be  used,  the  impression  and  bite  are  best  taken 
together  preferably  in  plaster,  or  impression  compound  maybe  used; 
or  the  bite  can  first  be  taken  in  wax,  then  the  impression  in  either  plas- 
ter or  impression  compound.  The  impression  and  "bite"  are  best 
taken  together  if  the  shape  of  the  teeth  permits  easy  removal.  To 
permit  easy  removal  of  the  cap  from  the  model  during  its  construction, 
a  veneer  of  paraffin  should  be  placed  with  a  heated  spatula  around  the 
inner  surface  of  the  collar  and  on  the  sides  of  the  posts.  (See  Part  I, 
Chapter  IV).  A  plaster  model  is  made,  the  wax  "bite,"  if  separate, 
adjusted  on  it  and  an  articulating  model  made. 

The  projecting  end  of  the  post  is  cut  off  with  a  thin  carborundum 
disk  a  little  above  the  surface  of  the  floor.     The  end  of  the  post  is  next 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS 


179 


reduced  with  a  carborundum  wheel  to  the  surface  of  the  floor  at  the 
labial  side,  but  left  slightly  projecting  above  it  lingually  for  additional 
strength,  should  such  a  form  offer  no  obstruction  to  the  setting  of  the 
porcelain  facing  (B,  Fig.  298). 

The  porcelain  facing  is  formed  of  a  cross-pin  plate  tooth.  The 
shade  selected  should  be  at  least  as  dark  as  that  of  the  opposite  cor- 
responding natural  tooth,  if  present,  or  if  absent  that  of  the  adjoining 
teeth.  The  general  form,  while  suitable  in  appearance,  should  be  such 
as  will  permit  proper  adaptation  without  excessive  reduction  by  grind- 
ing. The  curve  of  the  sides  toward  the  base  should  be  such  that  when 
the  facing  is  ground  the  base  will  not  greatly  exceed  the  surface  of  the 
cap  in  width,  and  the  pins  be  so  located  that  their  strength  will  not 
become  impaired  in  the  required  removal  of  the  porcelain  for  the  proper 
adjustment  of  the  facing. 

There  are  two  methods  of  setting  the  por- 
celain facing  to  the  cap.     In  the  first  metho  I 
the  facing  is  ground  to  position  with  the  bas 
of  the  porcelain  closely  fitted  to  the  surfac 
of  the  cap  (Fig.  299). 


Fig.  298.  Pig.  299.  Fig.  300. 

In  the  second  method  the  facing  is  fitted  at  the  cervico-labial  sec- 
tion to  rest  on  the  cap  while  the  remainder  of  the  base  is  ground  so  as  to 
form  a  slightly  increasing  space  toward  the  lingual  side  just  over  the 
post  (P,  Fig.  300).  As  the  porcelain  rests  on  the  cap  at  only  one  point 
it  simplifies  the  work  of  correctly  positioning  the  facing  with  the  other 
teeth.  The  facing  should  be  ground  so  as  to  locate  the  pins  a  little 
toward  the  incisal  edge  for  strength.  The  cervico-labial  edge  of  the 
facing  should  be  placed  even  or  flush  with  the  edge  of  the  collar.  When 
a  model  is  used  to  fit  the  porcelain  facing,  although  it  facilitates  the 
operation,  the  exact  alignment  of  the  facing  should  be  determined  by 
a  final  adjustment  in  the  mouth. 

To  Protect  the  Incisal  Edge  of  the  Porcelain  Facing. — To  protect 
the  incisal  edge  of  the  porcelain  facing  against  fracture  in  such  a  way 


i8o  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

that  the  gold  shall  be  invisible,  the  porcelain  should  be  ground  and 
beveled  ofif  at  an  angle  of  about  45  degrees  to  the  incisal  edge  at  a 
proper  distance  from  the  pins,  as  shown  in  Figs.  298,  299,  and  300,  and 
also  at  A,  Fig.  301.  In  grinding  and  polishing  the  porcelain,  revolve  the 
wheel  in  the  direction  shown  in  Fig.  312  to  avoid  chipping  the  enamel. 
Polish  the  edge  with  fine  sandpaper  disks.  In  the  final  finishing  the 
gold  is  brought  on  a  straight  line,  or  nearly  so,  with  the  edge  of  the 
porcelain,  as  shown  at  B,  Fig.  301.  By  this  plan  the  porcelain  is 
protected  and  the  gold  rendered  invisible  when  viewed  from  the  front. 

Backing  The  Porcelain  Facing 

One-Piece  Backing. — When  the  porcelain  facing  has  been  fitted  to 
the  cap  by  the  aid  of  a  model,  it  is  best  to  retain  and  define  its  position 
on  the  cap  before  removing  it  for  the  application 
of  the  backing,  by  forming  a  removable  matrix 
of  plaster  on  the  labial  aspect,  as  shown  in  Fig. 
302.  This  permits  removal  of  the  facing  and  in- 
sures its  replacement  when  backed  in  exact  posi- 
tion on  the  cap.  The  backing  of  the  facing  must 
be  absolutely  adapted  to  the  surface  of  the  porce- 
FiG.  302.  lain  to  afford  strengtTi  and  continuity  of  structure 

and  prevent  intrusion  of  secretions  or  extraneous 
matter  in  use.  To  effect  this  the  porcelain  facing  before  backing 
should  be  first  divested  of  every  particle  of  wax  by  immersing  in 
boiling  water.  The  edge  of  the  backing  should  be  flush  with  the  edge 
of  the  porcelain  on  the  sides  to  draw  the  solder  and  permit  finish.  The 
backing  should  never  be  rounded  or  looped  over  an  edge  of  the  porce- 
lain. The  backing  is  made  of  platinum,  gage  No. 
38,  or  crown  metal,  which  is  platinum  on  one  side 
and  gold  on  the  other,  or  of  24-carat  pure  gold 
plate,  gage  No.  30  to  31.  Gold  imparts  a 
slightly  yellow  and  platinum  a  bluish  shade  to 
the  porcelain;  So  the  platinum  or  gold  side  of  the  crown  metal  can  be 
placed  accordingly. 

When  the  entire  base  of  the  porcelain  facing  is  fitted  to  rest  on  the 
floor  of  the  cap  according  to  the  first-mentioned  method,  the  backing 
is  applied  to  extend  from  the  base  to  and  over  the  trimmed  incisal 
edge,  as  shown  in  Fig.  299.  If  the  facing  is  fitted  according  to  the 
second  method  with  a  V-shaped  space  at  the  lingual  side  of  the  base,  the 
backing  is  extended  to  also  cover  the  base,  as  shown  at  P,  Fig.  300. 
To  ascertain  the  exact  position  of  the  pins,  the  plate  is  placed  on  a  flat 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS 


wooden  surface  or  a  piece  of  cork,  the  pins  are  made  perfectly  straight 
and  the  facing  placed  over  the  plate,  pins  downward,  and  enough  pres- 
sure applied  to  make  a  slight  indentation  (Fig.  303).  Holes  are  now 
punched  through  the  indentations  with  punch  forceps  and  the  backing 
closely  adapted  to  the  surface  of  the  porcelain  by  annealing  and 
burnishing. 

Pointed-Pin  Facings  lately  introduced  are  intended  to  punch  their 
own  holes  through  a  backing  of  moderate  gage  by  pressure.  This 
simplifies  the  operation  of  backing  and  forms  a  flux-tight  joint  between 
pins  and  backing  that  prevents  solder  from  flowing  through  and  checking 
the  porcelain,  which  is  liable  to  occur  when  the  pin-holes  in  the  back- 
ing are  loose  or  open.     Fig.  304  illustrates  this  form  of  facing. 

Use  of  Swager. — An  assured  adaptation  of  a  backing  to  a  facing 
is  obtained  by  placing  the  facing,  labial  aspect  downward,  in  impres- 
sion-compound in  a  swager  cup  (Fig.  305),  and  swaging  the  backing 


Fig.  304. 


Fig.  305. 


Pig.  306.     Fig.  307.  Fig,  308. 


against  the  porcelain.  To  avoid  fracture,  the  backing  should  first  be 
burnished,  then  annealed  and  not  too  much  force  should  be  applied. 

When  the  backing  is  adapted,  the  pins  are  bent  down  on  the  surface 
in  either  of  the  positions  shown  in  Figs.  306  and  307.  When  bent  as 
in  Fig.  306,  they  assist  in  retaining  the  solder  in  position,  in  solder- 
ing and  thickening  the  backing  at  that  point.  The  backing  is 
trimmed  straight  to  the  sides  of  the  porcelain  except  at  the  incisal 
edge,  where  it  is  left  extended,  as  shown  in  Fig.  307.  This  extension  is 
removed  to  the  edge  of  the  porcelain  after  the  crown  is  soldered. 

Removal  of  a  small  portion  of  the  pins  on  the  side  they  are  to  be 
bent  (A,  Fig.  308)  with  a  stiff  sand-paper  disk  will  permit  them  to  be 
bent  downward  on  the  surface  of  the  backing  with  less  strain  upon  the 
porcelain.  The  backing  should  be  in  position  on  the  porcelain  when 
the  pins  are  trimmed  to  avoid  their  removal  below  the  line  of  the 
surface  of  the  backing;  preferably  they  should  be  trimmed  a  little 
above  it. 


1 82  CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 

Preparation  for  Investment. — The  porcelain  facing  when  backed  is 
adjusted  on  the  cap.  Should  the  metal  backing  on  the  base  of  a  facing 
in  the  second  method  interfere  with  its  proper  adjustment  on  the  cap 
at  the  cervico-labial  section,  as  is  generally  the  case,  it  should  be 
thinned  with  a  small  carborundum  cone  or  entirely  removed  at  the 
obstructing  point,  as  indicated  at  C,  Fig.  307,  and  that  portion  of  the 
porcelain  allowed  to  xest  directly  on  the  cap.  The  facing  is  first  at- 
tached to  the  cap  with  only  a  small  quantity  of  adhesive  wax  until  its 
alignment  is  quite  accurately  determined,  then  hard  wax  is  added  to 
more  securely  retain  it.  The  whole  is  chilled  in  cold  water 
and  a  final  adjustment  made  in  the  mouth  to  positively 
assuie  its  correctness.  Before  investing,  additional  wax  is 
added  to  the  metallic  paits  of  the  crown  to  be  soldered,  suf- 
ficient to  impart  to  them  the  desired  form  for  the  solder  and 
allow  a  slight  excess  for  finishing.  A  little  wax  is  generally 
Fig.  309.  placed  on  the  sides  of  the  collar  at  the  cervical  section  of  the 
porcelain  facing,  especially  when  any  portion  of  the  porcelain 
projects  over  the  line  of  the  collar,  for  the  purpose  of  providing  space 
in  the  investment  for  the  solder  to  flow  and  contour  the  part,  as 
shown  in  Fig.  309,  which  illustrates  the  waxed-up  crown  ready  for 
investment. 

Investment. — Calcined  marble-dust  or  fine  silex  and  plaster  are 
the  preferred  materials  for  investment.  They  are  used  in  the  propor- 
tions of  two  parts  marble-dust  or  silex  to  one  of  plaster.  First  thor- 
oughly mix  the  dry  ingredients,  then  add  the  water.  The  crown  is 
first  wet  by  dipping  in  water  and  then  the  ^,*^-w:?>, 

inside  of  the  cap  is  filled  with  the  investment  ^^z..,^.-M \ 

material.     A   small   camel's-hair   brush  will      f'  ''     ~~--~-,..\\  * 

facilitate  this;  also  the  use  of  a  hand  air-     K-  I 

syringe  to  blow  the  investment  into  the  in-      ^^^ 

terstices.     A  portion  of  the  investment  in  the  _, 

'^  Fig.  310. 

form  of  a  small  mound  is  next  placed  on  a 

sheet  of  paper  and  the  crown  is  gently  pressed  into  it  until  all  the 
parts  are  covered  except  the  wax  on  the  lingual  side  of  the  backing. 
When  the  investment  has  set,  the  wax  is  removed  by  pouring 
boiling  water  on  the  investment.  Instruments  should  not  be  used  to 
remove  wax  as  they  are  liable  to  disturb  delicately  adjusted  parts. 
The  investment  is  next  trimmed  and  reduced  in  size  as  much  as  it 
properly  can  be,  and  the  investment  material  removed  so  that  the 
metallic  parts  of  the  crown  are  slightly  exposed  at  the  sides,  as  shown 
in  Fig.  310,  for  the  first  described  method  of  fitting  a  facing,  and  in 
Fig.  311  for  the  second  method,  to  fully  expose  the  V-shaped  space. 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS  1 83 

Borax,  finely  ground  and  mixed  with  waler  or  liquid  flux,  is  applied 
with  a  brush  to  the  metallic  parls  and  in  the  seams  before  heating. 
When  Parr's  fluxed  wax  is  used  for  the  benefit  of  the  flux  it  contains, 
the  wax  is  allowed  to  burn  cut  as  the  investment  is  heated.  The 
objection  to  burning  wax  out  is  that  it  does  not  leave  as  clean  a 
surface  of  metal  to  solder. 

Soldering  and  Finishing. — The  investment  should  first  be  dried 
and  then  heated  to  a  dull  red  over  a  Bunsen  flame  (see  Part  I,  Chapter 
VII),  and  removed  to  a  soldering-block.  Gold  solder  cut  in  small 
pieces  in  quantity  only  sufficient  to  fill  interstices  and  unite  the  facing 
to  the  cap  is  first  placed  in  and  over  the  space  between  the  facing  and 
cap.  The  solder  should  have  been  previously  immersed  in  borax 
finely  ground  in  water  and  then  dried,  or,  after  it  is  placed  in  position, 
it  should  have  a  small  quantity  of  calcined  borax  sprinkled  over  it. 


Fig.  311.  Fig.  312.  Fig.  313. 

Solder  is  also  used  in  strip  form,  as  it  can  be  more  rapidly  applied 
and  the  application  instantly  stopped  by  withdrawing  the  strip.  Sol- 
dering of  places  difficult  to  reach  is  facihtated,  as  illustrated  in  Fig. 
315.  Heating  the  investment  uniformly,  especially  underneath,  and 
in  the  direction  indicated  by  A,  Fig.  311,  with  the  deoxidizing  section  of 
the  large  flame  of  a  gas  blowpipe,  will  cause  the  solder  as  it  melts  to 
gradually  flow  downward  into  the  interstices.  More  solder  is  added  by 
degrees  and  fused  in  this  manner  with  some  use  of  a  smaller  flame 
directly  applied  to  the  gold  until  the  spaces  between  the  porcelain 
facing  and  cap  and  at  the  sides  are  filled  in  and  continuity  of  structure 
assured.  After  letting  the  body  of  the  investment  cool  slightly,  so  as 
not  to  draw  hack  the  solder  that  has  been  already  fused  in  the  deep- 
portions,  additional  solder  is  placed  on  the  backmg  and  cap,  and 
with  a  small-pointed  flame  flowed  over  these  parts.  Only  sufficient 
gold  should  be  applied  to  properly  contour  the  parts  and  allow  for 
finishing.  When  soldered,  the  investment  should  be  allowed  to  cool 
slowly.  The  crown  is  next  removed  and  boiled  in  sulfuric  acid,  20 
per  cent.,  to  thoroughly  remove  the  borax,  and  it  is  ready  for  finishing. 


1 84  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

In  finishing,  the  movement  of  wheels  and  files  in  trimming  and  polish- 
ing should  be  so  directed  that  the  edge  of  the  metal  adjusted  to  the 
porcelain  is  pressed  against  it,  as  is  indicated  in  Fig.  312,  showing 
the  use  of  a  wheel  in  reducing  and  trimming  the  surplus  gold  at  the 
incisal  edge.  The  finishing  with  sandpaper  disks  should  be  done  in 
the  same  direction.     Fig.  313  represents  the  completed  crown. 

When  the  porcelain  projects  beyond  the  edge  of  the  collar  at  the 
cervico-labial  section,  as  shown  at  A,  Fig.  314,  and  the  form  will  not 
permit  of  sufficient  removal,  as  frequently  occurs  in  the  case  of  cuspids, 
the  space  left  should  be  evenly  filled  with  gold  solder  when  the  facing 
is  being  attached  to  the  cap.  To  accomplish  this  the  backing  applied 
to  the  base  of  the  facing  should  be  thinned  or  made  of  platinum  foil 
(see  PF,  Fig.  319),  and  extended  slightly  beyond  the  edge  of  the  porce- 
lain at  the  cervico-labial  section.     The  open  space  is  filled  and  shaped 


Fig.  314. 

evenly  with  wax  a  little  more  than  flush  at  the  edge  of  the  collar  and 
extended  backing.  In  such  cases  the  flow  of  solder  to  the  part  is 
effected  by  forming  a  space  on  each  side  and  through  the  investment 
which  will  expose  it  and  permit  solder  to  be  applied  directly,  preferably 
in  the  form  of  a  narrow  strip,  as  shown  in  Fig.  315. 


Diversity  of  Construction 

Method  of  Forming  Posts  to  Accurately  Fit  Canals.^ — To  form  a 
post  that  will  accurately  fit  a  canal,  especially  a  canal  that  for  some 
reason  is  considerably  enlarged,  slightly  taper  the  point  of  a  piece  of 
iridio-platinum  wire,  gage  No.  20  to  21,  and  a  half  inch  long,  fit  it  to  the 
extremity  of  the  canal  and  bend  the  end  of  the  wire  toward  the  labial 
side  at  a  right  angle  to  indicate  its  position  when  inserted  (Fig.  316), 
and  veneer  the  point  of  the  wire  with  pure  gold  by  fusing  on  it  a  pellet 
of  gold  foil.  Cut  a  strip  of  platinum  foil,  gage  3=-l!ooo>  about  one-eighth 
of  an  inch  wide  and  an  inch  or  more  in  length;  bend  the  end  of  the  strip 
of  foil  over  the  end  of  the  wire  close  to  the  point,  and  unite  the  wire  and 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS 


185 


foil  in  a  Bunsen  flame.  The  veneer  of  gold  at  the  point  of  the  wire  on 
fusing  will  be  just  enough  to  attach  the  strip  (A,  Fig.  317).  Next  wind 
the  strip  around  the  wire,  as  shown  at  B,  and  insert  in  the  canal.  The 
coils  of  foil  will  press  down  on  the  wire  in  conformity 
with  the  size  and  shape  of  the  canal,  as  illustrated  at 
C.  Seize  the  exposed  portion  of  the  foil  and  wire 
firmly  with  small-pointed  pliers,  remove  in  position 
and  solder  in  a  Bunsen  flame  with  pellets  of  gold 
foil.  Apply  only  enough  gold  to  unite  the  layers  of 
platinum,  for  if  an  excess  is  used  the  shape  of  the  post 
will  be  altered  and  it  will  not  fit  the  canal.  The  cor- 
rugations on  the  post  formed  by  the  layers  of 
platinum  foil  afford  an  attachment  for  the  cement. 

Hollow  Post. — This  consists  of  a  post  with  a  small  canal  running 
through  the  center.     The  advantage  it  offers  is  the  comparative  ease 
with  which  it  can  be  drilled  out  of  the  canal,  if 
\)      for  any  reason  it  becomes  necessary  to  remove 
the  crown,  as  the  drill  will  follow  the  hole  in 
the  center  of  the  post. 

Construction. — Select  the  smallest  carbon 
used  for  pencils '^  (A,  Fig.  318).  Heat  and 
veneer  the  surface  with  a  film  of  wax  cement. 
Cut  a  strip  of  platinum  foil  \iooQ,  at  least 
three-eighths  inch  wide  and  about  an  inch  long. 
Warm  the  carbon  enough  to  soften  the  veneer  of 
wax  and  attach  the  end  of  the  foil  the  same  as 
to  the  platinum  wire,  as  shown  at  A,  Fig.  317. 
Next  wind  the  foil  around  the  carbon  (A  and  B,  Fig.  318)  and  unite 
the  layers  of  foil  with  pure  gold.  The  carbon  may  be  removed  or 
allowed  to  remain.  The  gage  of  the  post  is  regulated  by 
the  quantity  of  foil  that  is  wound  around  the  carbon.  A      B 

To  Separately  Back  or  Veneer  the  Base  of  a  Porcelain 
Facing  with  Platinum. — This  method  consists  in  the  use  of  a 
piece  of  platinum  foil — instead  of  an  extension  of  the  backing 
— ^to  cover  the  base  of  the  porcelain  facing  when  a  V-shaped 
space  exists  between  the  porcelain  and  the  floor  of  the  cap, 
for  the  purpose  of  drawing  the  solder  into  the  space  so  that  Fig.  318. 
when  in  use  the  secretions  will  be  excluded. 


^ 


B 
Fig.  317. 


1  The  best  method  is  to  procure  the  hardest  made  drawing  pencil,  which  is  marked 
8H,  and  remove  a  piece  of  the  carbon  about  three-fourths  of  an  inch  long  and  trim 
it  down  in  a  chuck  on  the  lathe  to  about  No.  22  or  23  gage,  which  with  care  is  easily 
done. 


i86 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


The  process  is  as  follows:  The  base  of  the  facing  is  heated  and  its 
surface  veneered  with  adhesive  wax.  While  the  wax  is  in  a  melted 
condition,  a  piece  of  3^^0  0  0  platinum  foil  is  pressed  against  the  wax  with 
the  finger  or  a  tightly  twisted  ball  of  cotton  with  force  enough  to  squeeze 
out  the  hot  wax  and  bring  the  foil  close  to  the  porcelain  (PF,  Fig.  319). 
The  base  is  reheated  enough  to  soften  the  wax  and  pressure  is  again 
applied  until  the  foil  is  brought  against  the  porcelain.  The  surplus 
foil  is  cut  flush  with  the  porcelain  and  the  facing  is  then  mounted  on  the 
cap.  Platinum  foil  is  preferable  to  gold  because  less  liable  to  melt  and 
be  absorbed  by  the  solder.  The  foil  at  the  extreme  cervico-labial  edge 
may  be  removed,  as  illustrated  at  C,  Fig.  307,  as  in  the  case  of  a  plate 
backing,  and  that  portion  of  the  porcelain  permitted  to  rest  directly  on 
the  floor.     The  crown  should  be  invested  as  shown  in  Fig.  311. 


Fig.  319.  Fig.  320. 

Fig.   320. — lEB,    incisal  edge  backing;  B,  backing;    W, 
and  facing  on  cap. 

Fig.  321. — FB,  first  backing;  SB,  second  backing. 


Fig.  321. 
wax  to  retain  backing 


Two-F*iece  Backing. — The  one-piece  backing  previously  described 
is  the  one  most  used.  The  two-piece  backing  is  also  in  favor.  The 
lingual  surface  of  the  facing  alone  or  with  the  base  is  first  backed  with 
either  pure  gold,  gage  No.  30  or  31,  or  platinum  %000;  the  pins  bent 
and  the  backing  trimmed  to  the  line  of  the  porcelain,  as  shown  at  B, 
Fig.  320.  When  the  facing  is  mounted  on  the  cap  with  wax  ready  to 
invest  for  soldering,  an  incisal  edge  backing  of  either  gold  or  platinum 
is  added  and  attached  with  wax,  as  shown  at  lEB.  In  the  soldering, 
the  backing  to  the  porcelain  facing  is  first  soldered  and  connected  to 
the  cap,  then  the  solder  placed  on  the  incisal  edge  backing  and  the  two 
connected. 

Reinforced  Backing. — This  consists  of  first  adapting  a  backing  to 
only  the  lingual  or  both  lingual  and  base  surfaces  of  the  facing  and  then 
adapting  another  backing  over  the  first  which  will  also  include  the 
incisal  surface.     The  first  backing  (FB,  Fig.  321),  is  made  of  pure  gold, 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS  187 

gage  No.  32,  or  platinum  plate  Kooo  gage,  closely  adapted  or  swaged. 
The  second  backing  (SB)  of  20-carat  gold  plate,  gage  No.  26  to  30— 
the  lighter  the  first  backing  the  heavier  the  second— is  extended  from 
below  the  pins  to  and  over  the  incisal  surface.  It  should  be  carefully 
adapted  by  burnishing  and  annealing.     Punching  holes  in  the  second 


Fig.  322. 


backing  (E,  Fig.  322),  which  is  to  protect  the  incisal  edge  (C)  will 
permit  the  solder  to  flow  to  the  first  backing  (D)  and  unite  it  in  the 
soldering  of  the  facing  to  the  cap. 

Another  method  is  to  remove  the  backings  in  position  from  the 
facing  before  investment,  paint  the  under  side  of  the  first  backing  and 


Fig.  323- 

.fill  the  pin  hole  with  rouge  or  antiflux.  Next  clamp  the  backings  to- 
gether, as  shown  in  Fig.  323,  and  unite  them  with  solder,  using  no  more 
than  enough  to  barely  show  at  the  edges  of  the  seam.  The  double 
backing  when  adjusted  on  the  facing  will  appear  as  outlined  in  Fig. 
321. 


CHAPTER  X 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS,  CONTINUED 

BICUSPIDS  AND  MOLARS — TO  FORM  A  CUSP-CAP — INLAYING  PORCELAIN 
FACINGS  IN  GOLD  CROWNS — APPLICATION  TO  A  SEAMLESS  GOLD 
CROWN — INLAYING  PORCELAIN  FACINGS  IN  SECTIONAL  CROWNS — 
A  FAULTY  METHOD — CROWNING  IN  CASES  OF  ABRASION — ^GOLD 
CROWNS    WITH   PORCELAIN  FACINGS  FOR  TEETH  WITH  VITAL  PULPS 

Bicuspids  and  Molars. — Bicuspids  crowned  by  the  method  de- 
scribed for  incisors  and  cuspids  will  have  greater  strength  if  a  portion 
of  the  lingual  section  of  the  natural  crown  is  preserved  (Fig.  176), 
because  of  the  support  it  will  afford  to  the  collar  which  will  cover  it. 

The  end  of  the  root  is  capped  after  the  manner  of  the  typical  central 
already  described,  one  or  two  posts  being  used  in  the  canals  as  required. 
Where  only  one  post  is  used,  it  is  best  inserted  in  the  lingual  canal.  If 
desired,   a   "bite"   impression   is   then   taken    and  models  made.     A 


Fig.  324. 


Fig.  325. 


Pig.  326. 


Fig.  327. 


Fig.  328. 


porcelain  cuspid  tooth,  or  a  bicuspid  facing  is  then  ground,  backed  and 
adjusted  on  the  cap  to  represent  the  labial  aspect,  and  secured  with  wax. 
It  is  carefully  adjusted  in  the  mouth  and  the  occluding  edge  of  the  porce- 
lain ground  to  clear  the  antagonizing  teeth  (A,  Fig.  324). 

To  Form  a  Cusp-cap. — A  cusp-cap  is  made  by  one  of  the  methods 
described  in  Part  III,  Chapter  VII.  The  preferable  method — No.  6 — 
is  to  form  a  wax  model  of  the  cusp-cap  and  cast  it,  especially  if  the  oc- 
clusion is  abnormal.  When  a  cast  cusp-cap  is  used,  all  or  a  portion  of 
the  coronal  section  of  the  crown  to  the  floor  of  the  cap  maybe  addi- 
tionally included  in  the  casting,  as  illustrated  in  Fig.  325.  A  cusp-cap 
may  also  be  formed  by  stamping  a  disk  of  pure  gold,  gage  No.  34, 
with  a  suitably  sized  die  (Figs.  326  and  327),  or  by  the  use  of  a  cusp- 
button — Method  No,  4 — and  reinforcing  it  with  coin  gold. 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS 


189 


The  cusp-cap  when  formed  is  trimmed  (P'ig.  328),  ground  and  fitted 
to  the  occluding  edge  of  the  porcelain  facing  (Fig.  329J,  in  proper  posi- 
tion as  regards  occlusion,  and  the  wax  attaching  it  is  shaped  to  the 
contour  of  the  crown  (A).  A  piece  of  very  thin  pure  gold  plate  gage 
No.  40  or  Mo 00  platinum  foil  (B)  is  adjusted  on  each  approximal 
side  of  the  crown,  which  is  then  invested  (Fig.  330).  The  long  ends  of 
the  side  pieces  of  metal  are  designed  to  retain  them  in  position  in  the 
investment  so  that  the  investment  may  be  removed  from  the  portion 
enclosing  the  sides  of  the  crown  (A).  Mica  (isinglass)  may  also  be  used 
as  suitable  for  this  purpose  instead  of  gold  or  platinum.  In  the  process 
of  soldering  the  solder  is  placed  in  the  aperture  at  B  and  the  flame  of  the 
blowpipe  directed  under  the  investment,  then  on  the  exposed  sides  of 
the  metal  or  mica  at  A.  The  solder  is  thus  flowed  into  every  part, 
forming  perfect  continuity  of  structure  of  the  metallic  portion  of  the 
crown.  If  the  crown  is  short  and  the  aperture  at  A  is  left  open  without 
the  gold  or  mica,  and  the  solder  is  first  flowed  in  the  interstices,  as 


Fig.  330. 


Fig.  331. 


Fig.  332. 


described  in  soldering  an  incisor  crown,  the  remaining  solder  necessary 
to  contour  the  part  can  be  added  if  the  pointed  flame  is  used  and  not  too 
much  heat  applied  to  the  other  portions  of  the  crown  and  investment. 
In  finishing,  the  surplus  gold  is  trimmed  to  the  contour  of  a  bicuspid 
tooth.     Fig.  331  represents  the  finished  crown. 

In  difficult  cases  and  occlusions  the  work  is  simphfied  by  first  sold- 
ering the  porcelain  facing  to  the  cap.  The  crown  is  then  adjusted  in 
the  mouth  and  the  porcelain  ground  to  properly  clear  the  occluding 
teeth  and  allow  space  for  the  cusp-cap,  and  the  work  then  completed 
as  described. 

This  method  produces  a  perfect  and  artistically  formed  crown,  but 
simpler  and  quicker  methods  are  practiced.  One  of  these  is  to  build  up 
the  palatal  cusp  with  pieces  of  gold  plate  which  have  previously  been 
melted  into  globules  and  flattened  out  on  an  anvil.  These,  laid  in 
position  and  united  with  solder,  are  shaped  in  finishing  to  represent 
the  lingual  cusp  (Fig.  332).  The  porcelain  facing  should  be  backed  so 
that  the  solder  can  be  flowed  over  its  occlusal  edge. 


I  go 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Another  method  is  to  extend  the  palatal  part  of  the  collar  down, 
as  shown  in  Fig.  333,  and  then  fill  in  the  space  and  form  the  sides 
and  occlusal  surface  with  solder.  In  finishing,  the  gold  is  trimmed  to 
the  form  of  the  crown.  As  much  as  possible  of  the  natural  crown 
should  be  left  at  the  palatal  side  of  the  collar,  the  exposed  occlusal  edge 
of  which  may  be  slit  and  brought  in  against  the  side  of  the  tooth,  and 
soldered  to  give  contour.  With  this  form  of  collar  one  post  in  the 
lingual  root-canal  is  sufficient.  The  end  of  the  post  should  be  allowed 
to  extend  out  of  the  floor  of  the  cap  enough  to  just  touch  the  lower  teeth 
when  they  are  occluded.  The  exposed  end  of  the  post  will  be  an  exact 
guide  as  to  the  quantity  of  solder  required  to  form  the  occlusal  surface. 
In  this  and  in  the  method  previously  described,  the  porcelain  facings 
may  be  soldered  and  the  lingual  cusp  formed  in  one  investment. 

The  method  of  construction  of  molar  crowns  with  porcelain  facing 
is  similar  to  that  of  bicuspids  (Fig.  334). 

Inlajdng  Porcelain  Facings  in  Gold  Crowns. — In  this  method  the 
porcelain  facing  is  inlaid  or  set  after  the  construction  of  the  gold  crown. 
The  crown  used  may  be  either  seamless  or  one 
constructed  in  sections,  but  the  seamless  crown 
is  preferable. 


Fig.  333.         Fig.  334.     Pig.  335.  Fig.  336.         Fig.  337 


Application  to  a  Seamless  Gold  Crown. — A  seamless  gold  bicuspid 
crown  will  be  used  to  explain  the  method.  The  crown  is  fitted  to  tooth 
or  root  and  the  occlusal  surface  reinforced,  using  Corona  gold  and  solder 
— preferably  hard  solder — and  boiled  in  acid  to  remove  all  flux.  (See 
Fig.  387.)  The  crown  is  adjusted  in  the  mouth  and  a  mark  made  with 
a  pointed  instrument  on  the  labial  face  of  the  gold  to  indicate  where  the 
porcelain  facing  is  to  appear  (Fig.  335).  The  crown  is  removed  and  the 
marked  piece  of  gold  is  cut  out  with  a  saw  or  a  knife-edged  wheel  (Fig. 
336),  and  the  edge  of  the  gold  beveled  to  receive  the  facing  when  backed 
(Fig.  337).  Grind  the  facing  (Fig.  338)  to  accurately  fit  the  space 
(Fig.  339).  Next  back  the  facing  with  pure  gold,  gage  No.  36,  extend- 
ing the  gold  just  over  the  edges,  annealing  and  burnishing,  or  swaging, 
to  secure  accurate  adaptation  (Figs.  340  and  341).  Trim  backing  to 
one-sixteenth  of  an  inch  of  the  edge  of  the  porcelain.  Adjust  facing 
and  backing  in  crown  and  attach  the  backing  to  the  crown  by  flowing 
wax  along  the  seam  at  the  edge  of  the  backing  inside  and  outside  the 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS  igi 


crown.  Next  remove  the  porcelain  facing,  leaving  the  hacking  attached 
to  the  gold  crown.  Invest  as  shown  in  Fig.  342,  paint  exposed  surface 
of  the  backing  with  rouge,  and  solder  the  edges  of  the  backing  to  the 
gold  crown,  using  as  little  solder  as  possible.  Shorten  the  pins  in  the 
porcelain  facing,  insert  it  in  position  in  the  backing  (Fig.  343)  and  slit 
the  ends  of  the  pins.  Invest,  as  indicated  in  section  in  Fig.  344,  and 
unite  pins  to  backing  by  doing  the  soldering  on  the  inside  of  the  crown. 
A  ver>  small  quantity  of  14-carat  or  very  easy-flowing  solder  filings 
should  be  used,  the  investment  well  heated  and  solder  fused  with  a 
small  pointed  flame. 


Fig.    339. 


Fig.  342. 


Fig.   343. 


Pig.    340. 


Pig.  341- 


Fig.  344. 


Fig.  345- 


This  last  described  soldering  may  also  be  done  by  wrapping  the 
crown  in  asbestos  paper,  winding  around  it  a  wire  and  suspending  in  a 
Bunsen  flame  (Fig.  345). 

In  finishing,  remove  surplus  edge  of  backing  around  the  porcelain, 
burnish,  trim  and  polish. 

Inlaying  Porcelain  Facing  in  Sectional  Crown. — The  occlusal  surface 
of  the  gold  crown  should  be  made  of  gage  No.  36  to  38  pure  gold,  rein- 
forced with  coin  gold  and  united  to  the  collar  by  sweating  or  with  hard- 
flowing  solder.  The  constructive  details  of  the  inlaying  of  the  porcelain 
facing  are  similar  to  the  method  already  described  except  that  the  pins 
of  the  facing  are  preferably  first  soldered  to  the  backing.  The  facirig 
and  backing  are  inserted  in  position  in  the  crown,  the  edge  of  the  back- 
ing attached  all  around  with  wax,  both  inside  and  outside  of  the  crown, 
and  the  crown  invested.     The  soldering  of  the  seam  around  the  facing 


192 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


is  more  safely  done  by  investing  so  as  to  expose  and  solder  only  one-half 
of  the  seam  first,  then  reinvest  and  do  the  other  half. 

A  Faulty  Method  of  forming  bicuspid  crowns,  especially  in  a  close 
occlusion,  and  therefore  one  to  avoid,  is  the  shaping  of  the  lingual  side, 
as  shown  at  W,  in  Fig.  346.  The  occlusal  surface  should  be  shaped  so 
that  the  cusp  of  the  occluding  tooth  shall  be  interlocked  in  occlusion, 
as  illustrated  at  R,  instead  of  glancing  off.  In  the  latter  event,  the 
root  is  liable  in  time  to  be  forced  outward  and  loosened. 

Crowning  in  Cases  of  Abrasion. — In  a  case  of  extensive  abrasion 
of  the  incisal  edges  of  the  anterior  teeth  with  vital  pulp  considerably 
calcified  in  the  coronal  section,  crown-work  to  restore  the  length  and 
form  of  the  teeth  is  best  performed  by  removing  a  portion  of  the  labial 
aspect  in  the  preparatory  operation  of  trimming  the  natural  crown  (Fig. 
347),  and  forming  the  artificial  crown  similar  to  a  gold  collar  crown  with 
a  porcelain  facing  without  a  post.     Fig.  348  gives  the  outline  of  the 


Fig.  347.         Fig.  348.         Fig.  349. 
Fig.  348. — RC,  root  cap;  SS,  soldered  section. 


Fig.  350. 


construction  of  such  a  crown.  If  a  case  having  the  natural  crown  worn 
down  very  short  should  suggest  the  necessity  of  a  post,  a  short  one 
can  be  inserted  between  the  line  of  the  pulp-chamber  and  the  lingual 
wall.  In  case  the  tooth  is  pulpless,  the  canal  can  be  opened  and  the 
post  extended  into  the  root. 

The  incisal  edge  of  the  porcelain  should  be  well  protected  by  the 
use  of  clasp  gold  and  solder  instead  of  the  ordinary  gold  plate.  When 
an  incisal  surface  of  considerable  thickness  is  suggested,  it  is  best  built 
to  the  desired  length  after  the  first  protecting  piece  has  been  soldered,  by 
applying  successive  layers  of  plate  rolled  thin,  of  the  size  of  the  incisal 
edge,  each  being  perforated  with  two  or  three  holes  with  punch  forceps, 
so  that  the  solder  shall  more  easily  flow  between  and  unite  them.  (See 
article  on  "Gold  Tips,"  Part  III,  Chapter  XVIII.) 

Gold  Crowns  with  Porcelain  Facings  for  Teeth  with  Vital  Pulps. 
In  the  anterior  teeth,  in  a  case  of  atrophy,  erosion  or  where  decay  has 
destroyed  the  approximal  sides  of  a  tooth  in  such  manner  that  crowning 


GOLD  COLLAR  CROWNS  WITH  PORCELAIN  FACINGS  193 

is  considered  desirable,  the  pulp  is  frequently  found  unexposed  and  in  a 
normal  condition.     Its  preservation  in  such  a  case  is  desirable. 

The  crowning  of  such  teeth  with  gold  jacket-crowns,  carrying  a  por- 
celain facing  attached  with  solder  is  generally  a  questionable  procedure, 
unless  considerable  calcification  of  the  pulp  exists,  as  the  room  required 
for  the  gold  and  the  small  space  left  for  the  porcelain,  together  with 
the  difificulty  of  securely  attaching  the  latter,  renders  such  a  construc- 
tion impracticable.  Jacket-crowns  for  such  cases  are  best  made  of 
porcelain.     (See  Part  VI,  Chapter  VII.) 

When  calcification  of  the  pulp  has  progressed  so  as  to  permit  con- 
struction of  a  crown  with  gold  and  porcelain,  the  natural  crown  should 
be  reduced  as  much  as  possible,  especially  on  the  labial  side.  It  is 
then  capped,  as  outlined  in  section  Fig.  349,  and  a  porcelain  facing 
ground,  fitted  and  adjusted  on  the  gold  cap.  The  facing  is  then 
soldered  to  the  cap  and  the  cap  reinforced,  as  seen  in  Fig.  350. 


13 


CHAPTER  XI 

THE  GOLD  SEAMLESS  CAP-CROWN  SYSTEM 

SEAMLESS  ROOT-CAPS  FOR  INCISOR,  CUSPID  AND  BICUSPID  CROWNS  WITH 
PORCELAIN  FACINGS — IMPRESSIONS  AND  DIES — METHOD  OF  STAMP- 
ING SEAMLESS  METAL  CAPS — ALL-GOLD  SEAMLESS  BICUSPIDS  AND 
MOLARS — ALL-GOLD  SEAMLESS  INCISORS  AND  CUSPIDS 

This  method  consists  in  the  use  of  a  gold  seamless  cap  for  the  con- 
struction of  the  required  root-cap  or  crown.  Through  improved 
methods  seamless  root-caps  and  crowns  can  be  used  by  those  versed  in 
the  method,  to  largely  answer  the  purposes  of  caps  constructed  in 
sections. 

Seamless  Root-Cap  for  Incisor,  Cuspid  and  Bicuspid  Crowns  with 
Porcelain  Facing. — The  advantage  of  this  style  of  cap  is  simplicity,  as 
the  formation  of  a  collar  is  avoided. 


Fig.  351. 


Pig.  353. 


For  a  seamless  root-cap  the  natural  crown  is  ground  down  to  within 
one-eighth  of  an  inch  of  the  gum  at  the  lingual  wall,  or  enough  to  fully 
clear  the  antagonizing  teeth  when  occluded,  and  slanting  from  the  lingual 
side  of  the  pulp-chamber  to  or  slightly  under  the  cervico-labial  edge  of 
the  gum.     The  periphery  is  shaped  the  same  as  for  a  collar  crown. 

For  a  partial  seamless  root-cap,  which  avoids  extension  of  the  collar 
around  the  cervico-labial  section  (Fig.  351),  that  side  of  the  root  is  left 
intact,  as  shown  at  A,  Fig.  352. 

Impressions  and  Dies. — A  die  of  the  end  of  the  root  is  first  made. 
For  this  purpose  an  impression  is  taken  in  a  tube  about  an  inch  long 
formed  of  a  strip  of  copper,  or  in  a  ready-made  tube  such  as  are  sold 
for  the  purpose.     The  tube  must  be  the  size  of  the  end  of  the  root. 

194 


THE  GOLD  SEAMLESS  CAP-CROWN  SYSTEM  195 

It  should  be  first  cut  and  shaped  to  the  curve  of  the  gum  so  that  the 
edge  fits  uniformly  well  under  the  free  margin,  especially  at  the  lingual 
side  (Fig.353).  The  impression  is  best  taken  with  impression  compound. 
It  should  be  heated,  the  tube  entirely  filled  with  the  compound  and  the 
end  to  take  the  impression,  again  heated  sufficiently  to  render  that 
part  of  the  compound  very  soft  just  before  being  applied  to  the  root. 
The  tube  is  then  adjusted  and  pressed  to  position  on 
the  root,  held  firmly,  and  the  extra  compound  which 
has  been  forced  out  of  the  other  end  of  the  tube 
pressed  on  by  the  finger  and  so  held  with  the  tube 
in  position,  until  the  compound  cools.  The  cooling 
may  be  hastened  by  applying  a  stream  of  cold  water 
with  a  syringe. 

When  the  tube  is  removed  the  impression  of  the 
root  end  will  be  found  proportionately  as  perfect  as 
an  impression  procured  for  the  formation  of  an 
inlay  by  the  indirect  method.  Form  the  die  of  amal-  p^^ 
am  and  the  result  will  be  as  near  an  approach  to 
a^bsolute  accuracy  in  detail  as  it  is  possible  to  procure.  The  amalgam 
must  be  thoroughly  mixed  and  carefully  packed,  as  described  in  Part 
I,  Chapter  V,  and  allowed  to  set  until  the  next  day.  Plaster  may  be 
used  instead  of  impression  compound  to  take  the  impression  in  the 
tube  and  the  die  cast  immediately  of  fusible  metal,  but  it  will  lack  the 
accuracy  in  detail  obtained  by  the  previous  method 
with  amalgam.  The  die  when  removed  from  the 
impression  should  be  lengthened  by  removing  from 
the  cervix  about  one-eighth  of  an  inch  of  the 
shoulder  of  metal  formed  by  the  edge  of  the  im- 
pression tube  (shown  at  T,  Fig.  354),  to  the  dotted 
line  marked  L.  The  lengthening  should  be  ac- 
complished without  altering  or  marring  the  die  in 
the  slightest  degree.  The  trimming  is  preferably 
Fig.  355.  done  with  a  chisel  resting  against  the  side  of  the 

die,  pointed  in  a  downward  direction  toward  the 
shank,  then  smoothed  with  a  file.  A  fissure  bur  also  assists  in  remov- 
ing surplus  metal.  The  bur  should  be  positioned  at  a  right  angle  to 
the  shank  and  revolved  so  that  it  will  be  thrown  downward  on  the 
shank  instead  of  upward  on  the  die.  The  die  is  next  mounted  in  a 
swager  cup,  as  outlined  in  Fig.  355,  and  described  in  Part  I,  Chapter 
V.  As  the  fine  lines  of  an  amalgam  die  would  be  impaired  by  the 
preliminary  shaping  of  the  cap,  a  duplicate  in  fusible  metal  should  be 
made  and  first  used  to  shape  the  cap  and  then  the  amalgam  die  to 


196 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


give  it  the  finish.  To  do  this  quickly  and  easily,  press  the  mounted 
amalgam  die  down  into  the  surface  of  a  flat  piece  of  moldine,  remove 
and  place  the  cup  of  the  s wager  over  the  mold  and  fill  the  cup  with 
fusible  metal  through  the  hole. 

Method  of  Stamping  Seamless  Metal  Caps.^ — The  gold  plate  gen- 
erally used  for  seamless  caps  is  22  carats,  or  platinized  gold  23  carats, 
termed  non-oxidizable  gold,  gage  No.  29  to  30.  The  gold  plate  is 
first  cut  in  a  circular  piece  by  a  disk  cutter.  It  is  next  pressed  through 
a  steel  die-plate  with  punches  gaged  to  the  holes.  Each  time  the 
disk  is  punched  only  a  small  portion  of  the  gold  is  turned  over,  thus 

preventing  it  from  lapping  or  creas- 
ing. A  properly  constructed  press 
should  be  used  for  the  purpose,  such 
as  is  illustrated  in  Fig.  356. 

The  cap  (A,  Fig.  355)  is  annealed 
and  swaged  on  the  die  to  the 
typical  form  B.  The  palatal  portion 
of  the  cap  should  be  allowed  to  go 
well  up  under  the  free  margin  of  the 


In  the  process  of  adjustment, 


Fig.  356. 


Fig.  357.         Fig.  358.       Fig.   359. 


edges  that  fit  under  the  gum  should  be  marked  and  trimmed  as  directed 
in  describing  the  construction  of  a  collar  crown  and  then  burnished 
close  to  the  sides  of  the  root  and  into  the  orifice  of  the  root-canal, 
forming  a  perfect-fitting  seamless  cap  (Fig.  357).  In  cases  of  partial 
caps  not  all  the  gold  at  and  over  the  cervico-labial  edge  should  be 
removed  until  the  post  has  been  soldered.  An  iridio-platinum  post 
is  next  fitted  in  the  root-canal  and  soldered  to  the  cap  (Fig.  358)  as  in 
the  construction  of  the  gold  collar  crown  with  porcelain  facing  (Chapter 
VIII),  with  which  operation  the  remainder  of  the  process  of  construc- 
tion is  identical.  Fig.  359  represents  the  completed  crown  in  section. 
All-gold  Seamless  Bicuspids  and  Molars. — All-gold  seamless 
crowns  for  bicuspids  and  molars  that  will  accurately  fit  the  natural 


THE  GOLD  SEAMLESS  CAP-CROWN  SYSTEM  197 

crown  and  root  and  occlude  properly  with  the  antagonizing  teeth  are 
formed  as  follows:  The  natural  crown  is  jjroperly  prepared.  If  de- 
cayed or  broken  down  on  the  side,  it  should  be  shaped  up  with  amal- 
gam (Part  III,  Chapter  III).  A  copper  tube — seamless  or  soldered — 
is  accurately  fitted  to  the  prepared  tooth.  At  the  cervix  it  is  placed 
the  same  distance  under  the  gum  margin  as  for  a  gold  crown.  An 
impression  is  then  taken  in  compound  and  an  amalgam  die  made 
(Part  I,  Chapter  V).  Lengthen  the  neck  and  taper  the  shank  of  the 
die.  Take  a  wax  "bite"  and  then  an  impression  in  wax  or  compound. 
If  you  intend  to  remove  the  die  from  the  model  veneer  the  shank  with 
wax.  Insert  the  die  in  the  imprint  of  the  tooth  in  the  impression  and 
run  a  plaster  model.  On  removal  of  the  impression  the  die  will  be 
found  in  position  in  the  model  an  exact  replica  of  the  tooth  in  the 
mouth  (Fig.  360).  The  wax  "bite"  is  then  adjusted  and  an  articu- 
lating model  made.  Drill  one  or  more  holes  in  the  occlusal  surface 
of  the  die  and  do  any  necessary  shaping  or  contouring  of  the  form  of  the 


Fig.  360.  Fig.  361. 

tooth  with  hard  wax  or,  better  still,  oxyphosphate.  A  space  should 
be  left  between  the  antagonizing  teeth  and  the  occluding  surface, 
and  between  the  approximal  teeth  the  thickness  of  the  gage  of  gold  to 
be  used  (Fig.  361). 

An  impression  is  taken  of  the  amalgam  die  in  a  tube  with  moldine 
and  a  fusible  metal  die  run.  The  die  on  which  a  gold  cap  is  swaged 
should  always  be  lengthened  at  the  neck  so  that  the  crown  when  con- 
structed shall  have  a  surplus  in  depth  of  gold  to  allow  for  any  trimming 
of  the  collar  that  may  be  required  (A,  Fig.  362).  A  s wager  is  used  as  a 
counter-die  or  a  counter-die  (B)  can  be  made  by  punching  a  hole  in  a 
block  of  lead  and  hammering  the  die  into  it.  (See  Part  I,  Chapter  V.) 
The  cap  (A,  Fig.  363),  gage  No.  29  to  30,  is  placed  on  the  die,  tapped 
with  horn  hammer  to  the  general  shape,  and  with  the  aid  of  the  swager 
or  counter-die  swaged  to  the  form  of  the  crown  (B).  When  a  lead 
counter-die  is  used  an  allowance  for  the  thickness  of  the  gold  should 
be  first  made  by  driving  the  die  with  two  thicknesses  of  kid  into  the 


igS 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


counter-die  to  enlarge  it.  If  this  space  is  not  made  the  gold  is  liable 
to  be  torn  in  the  swaging.  A  piece  of  kid  leather  or  rubber-dam 
should  be  used  to  cover  and  protect  the  gold  cap  in  the  swaging  and 
facilitate  its  removal  from  the  counter-die. 

The  amalgam  die  is  next  divested  of  the  wax  or  oxyphosphate 
contouring  material  which  was  added  to  its  surface,  and  it  is  restored 
to  the  original  form  of  the  tooth  in  the  mouth.  The  gold  crown  is 
then  adjusted,  trimmed  to  the  curve  of  the  gingiva  at  the  cervix  and 
burnished,  and  it  is  ready  for  adjustment  in  the  mouth. 

The  method  described  is  the  most  approved.  Another  method  is 
to  fit  a  copper  collar  to  the  periphery  of  the  root,  take  a  "bite,"  then 


Pig.  362. 


Fig.  363. 


Pig.  364. 


an  impression  that  will  remove  the  collar  in  position,  and  run  plaster 
models.  When  the  models  are  made,  slit  and  remove  the  copper 
collar.  This  gives  a  plaster  form  of  the  tooth,  which  is  built  up  and 
shaped  to  the  required  form  of  the  crown  and  the  crown  then  made  by 
it,  as  in  the  preceding  method. 

All-gold  Seamless  Incisors  and  Cuspids.' — Incisor  and  cuspid  crowns 
from  which  a  portion  of  the  gold  on  the  labial  aspect  is  to  be  removed 
(see  Open-faced  Crowns,  Part  IV,  Chapter  IV)  or  which  are  to  be  used 
entire  as  supports  for  bridge-work  can  usually  be  advantageously 
formed  with  seamless  caps  (Fig.  364).  The  necks  of  these  crowns 
often  have  to  be  contracted  in  fitting  by  slitting,  lapping  and  soldering. 


CHAPTERXII 

IMPARTING  CONTOUR  TO  SEAMLESS  GOLD  CROWNS 

CROWNS  SWAGED  ON  DIES — METHOD  OF  SLITTING  AND  CONTRACTING 
THE  NECK — USE  OF  CONTOURING  PLIERS — EXTERNAL  APPLICA- 
TION OF  CONTOUR — TO  CONTOUR  ON  THE  DIE  WITH  A  SWAGER — 
SECTIONAL  MOLD  METHOD — FORMATION — SHAPING  THE  CAP 

Crowns  Swaged  on  Dies 

Method  of  Slitting  and  Contracting  the  Neck. — Crowns  for  cases 
in  which  decay  has  extensively  involved  the  approximal  sides,  owing  to 
encroachment  of  the  adjoining  teeth,  generally  require  very  little  if  any 
contouring.     It  should  be  borne  in  mind  that  a  swaged  seamless  crown 
at  the  approximal  surfaces  is  always  the  thickness  of  the,  gage  of  the 
gold  cap  larger  in  circumference.     Some  form  can  be  imparted  to  a 
swaged  straight-sided  seamless  crown  by  slitting  the  collar  directly  in 
the  center  of  the  lingual  side,  contracting  the  neck, 
tapering  the  underlapping  portion,  adjusting  on  the     ^fc^  /^^ 
tooth,  burnishing  the  gold,  removing  and  soldering     |:  R  ,:i|||i  l/iMl 
(Fig.  365).     This  contraction   also  imparts  a  very     i|||Pr    ^ip^ 
close  fit  to  the  neck.     When  more  contour  is  required         pj^,   ^65. 
than  that  obtained  by  the  thickness  of  the  gold  plate 
that  covers  the  die,  the  crown  may  be  formed  with  the  desired  size 
and  shape  of  occlusal  surface  and  then  slit  and  contracted  at  each  of 
the  approximal  sides,  fitted  and  soldered. 

Use  of  Contouring  Pliers. — Contouring  pliers  are  used  to  give  form 
to  a  seamless  crown  sufficient  to  knuckle  it  against  the  adjoining  teeth, 
but  the  bulge  that  is  imparted  by  this  means  is  not  located  close  enough 
to  the  occlusal  surface,  where  it  is  most  required. 

External  Application  of  Contour.^ — Contour  may  be  added  to  a 
seamless  gold  crown  by  soldering  so  as  to  knuckle  in  a  very  accurate 
form  to  an  adjoining  tooth  or  teeth  as  follows:  When  the  gold  crown 
has  been  fitted  and  articulated  heat  the  crown  and  veneer  the  approximal 
surfaces  with  sticky  wax.  Soften  two  pellets  of  adhesive  wax  and  press 
and  shape  them  against  the  sides  of  the  gold  crown.  Adjust  the  crown 
on  the  tooth  and  press  both  crown  and  wax  to  position  and  occlude 
teeth.     Remove  and  trim  wax  to  exact  form  of  desired  contour.     Place 

199 


200  CROWN-,  BRIDGE;  AND  PORCELAIN-WORK 

over  the  surface  of  the  wax  representing  the  approximal  surfaces  a 
layer  of  platinum  foil  ^^ooo>  as  marked  PF,  Fig.  366.  Reinsert  crown 
in  mouth,  occlude  teeth  and  remove.  Invest  crown,  leaving  occlusal 
surface  of  wax  exposed  as  shown  in  Fig.  367.  Burn  out  wax  or  remove 
with  hot  water.  Pack  pellets  of  Corona  gold  between  the  crown  and 
platinum  foil  to  prevent  the  foil  being  drawn  from  position  in  soldering. 
Heat  and  flow  solder  or  coin  gold  if  cap  is  made  of  platinized  gold, 
into  the  space  occupied  by  the  Corona  gold,  between  the  crown  and 
the  platinum  foil,  trim  and  polish.  This  method  gives  a  close,  accu- 
rate knuckling  for  a  seamless  crown  or  any  form  of  constructed  crown 
to  which  it  is  applied.  Coin  gold  or  hard  solder  should  be  used  to 
contour  when  the  crown  is  to  support  bridge- work,  so  as  to  jnaintain  the 
form  of  contour  in  subsequent  soldering.  In  the  case  of  a  single  crown, 
20-carat  solder  is  suitable. 

To  Contour  on  a  Die  with  a  Swager.— A  seamless  crown  may  be 
given  a  moderate  amount  of  contour  on  the  swaging  die  in  the  follow- 
ing manner :  Form  a  model  of  the  crown  with  the  addition  of  the  required 


Fig.  367. — SS,  spaces  to  be  filled. 

contour,  take  a  plaster  sectional  impression  formed  longitudinally 
in  halves  (See  Part  I,  Chapter  IV),  and  cast  a  die  of  fusible  metal  that 
melts  below  the  boiling  point  of  water.  Place  oyer  the  die  a  tight- 
fitting  seamless  gold  cap,  swage  the  occlusal  surface  if  a  bicuspid  or 
molar,  then  mallet  and  burnish  the  gold  lengthwise  as  closely  as  pos- 
sible to  the  die.  Next  mount  the  die  in  a  swager  by  inserting  the  base 
in  impression  compound  (Fig.  368).  Swage  the  gold  cap  to  the  sides, 
using  moldine  or  fine  shot  in  the  swager.  When  the  swaging  is  com- 
pleted, remove  the  die  from  the  crown  by  placing  it  in  boiling  water 
to  melt  out  the  fusible  metal.  Should  any  of  the  metal  adhere  to  the 
gold,  remove  it  by  placing  the  crown  in  nitric  acid. 

Sectional  Mold  Method. — The  artistic  requirement  of  all-gold 
crown-work  is  that  it  shall  reproduce  the  anatomical  contour  of  the 
natural  teeth.  Such  a  form  can  be  given  seamless  gold  bicuspid  and 
molar  crowns  by  the  sectional  mold  method  (Figs.  369,  370  and  371).^ 

iThis  is  the  style  of  molds  as  originally  introduced  by  the  author  in  1888. 


IMPARTING  CONTOUR  TO  SEAMLESS  GOLD  CROWNS  201 


Formation. — To  describe  and  illustrate  the  process,  fit  a  collar  of 
copper,  No.  30  gage,  knucl<le  it  against  the  approximal  teeth  and  trim 
the  edge  to  clear  the  antagonizing  teeth  in  occlusion.  Place  cement 
or  plaster  in  the  occlusal  end  of  the  collar  only  and  occlude  the  teeth. 
When  set,  remove,  trim  and  shape  to  the  desired  form  for  gold  crown. 
Shaping  the  Cap. — Flasks  are  now  manufactured  and  sold  to  facil- 
itate the  formation  of  a  metallic  sectional  mold.  Fig.  372  illustrates 
a  flask  of  this  kind,  termed  a  dividing  mold  cup.  Place  the  model — 
neck  downward  and  cusps  up — in  the  center  of  a  cake  of  moldine 

(Fig.  373).  Set  the  dividing  cup 
over  it — small  hole  up— with  the 
ribs  of  the  cup  opposite  either  the 
long  or  short  axis  (diameter)  of 


Fig.  371. 


Fig.  372. — 
Dividing  mold 
cup,  ^  size. 


the  crown.  Melt  fusible  metal  and  pour  through  the  small  opening  of 
the  cup,  completely  filling  it.  Melt  off  surplus  metal  with  a  hot  wax 
spatula  or  cut  it  off  with  a  strong  plaster  knife.  Now  set  cup  and 
mold  in  the  knock-out  block  (Fig.  374),  and  with  a  light  tap  on  the 
punch  (Fig.  375)  placed  on  the  metal  exposed  at  the  small  orifice  of  the 
ring,  remove  mold  from  ring. 

While  the  mold  is  still  warm  open  the  handles  of  the  splitter  (Fig. 
375)  sufficiently  to  insert  the  blades  in  the  grooves  formed  by  the 
ribs  of  the  mold  cup,  and  with  a  gentle  steady  pressure  split  the  mold 
through  the  center  and  remove  the  crown  model.  The  two  halves  of 
the  mold  will  go  together  perfectly,  forming  a  matrix  for  the  reception 
of  the  gold  cap  or  shell.  Form  or  select  a  gold  cap,  comparing  the  wire 
root  measurement  for  size;  anneal  the  cap,  carefully  vaselin  the  sur- 
face and  place  it  in  the  two  halves  of  the  split  mold.     Place  the  split 


202 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


mold  with  cap  back  into  the  mold  cup  and  with  a  soft  pine  wood  stick 

press  in  the  cap  sufi&ciently  to  seat  it  in  the  mold  and  by  hammering  on 

the  end  of  the  stick  partially  form  the  cusps.     Remove  the  pine  stick 

and  fill  the  shell  with  soft  unvulcanized  rubber,  place  cup  with  mold  and 

shell  in  the  base  of  the  swager,  the  cylinder  of  which  is  partly  filled  with 

moldine  covered  with  a  disk  or  rubber-dam,  and  swage  down  two  or 

three  times.     To  facilitate  the 

process,  remove  the  cap,  then 

the  rubber    from   the    inside, 

anneal  and  re-swage  until  the 

cap  assumes  the  form  of  the 

mold.     When  swaged,  boil  the 

crown  in  acid,  trim  and  polish. 

Fig.    376   shows   the   finished 

crown.     This  method  gives  a 

crown  of  the  exact  size  desired, 

accurate  in  articulation  and  in 

fit  at  the  cervical  margin. 


Fig.  373. 


Fig.  374. — Knock-out  block, 
^i  size. 


Fig. 


375. — Mold  splitter,  %  size;  punch, 
M  size. 


Another  method  to  form  a  mold  that  will  avoid  bubbling  of  the 
fusible  metal  in  pouring  is  as  follows:  Hold  the  plaster  tooth' — occlusal 
side  down — mounted  on  a  sprue  wire  in  pliers,  supported  so  that  it  will 
be  suspended  down  in  the  center  of  the  dividing  mold  cup,  with  the 
cervical  margin  below  the  edge  of  the  cup.  Heat  fusible  metal  and 
pour  into  the  cup  around  the  plaster  tooth.  When  set,  remove  cup, 
split  mold  while  hot  and  remove  plaster  model,  as  in  the  preceding 
method. 


CHAPTER  XIII 


ADJUSTMENT  OF  SEAMLESS  GOLD  CROWNS 


EXPANSION  or  THE  COLLAR  AND  CROWN — ALTERATION  OF  A  SIDE  OR 
PART  OF  A  CROWN — ALTERATION  OF  THE  OCCLUSAL  SURFACE — 
TO  DEEPEN  THE  CUSPS — TO  POINT,  LENGTHEN  OR  NARROW  THE 
BUCCAL  CUSP  IN  APPEARANCE — TO  LESSEN  OR  REMOVE  THE  INDENTA- 
TION BETWEEN  CUSPS — STRENGTHENING  AND  REINFORCEMENT  OF 
SEAMLESS  GOLD  CROWNS — METHOD  OF  FORMING  A  SOLID  OCCLUSAL 
SURFACE — EXTERNAL  REINFORCEMENT  WITH  PLATINUM  AND  GOLD 
IN  ''close  bites" — SOLID  GOLD  SEAMLESS  DUMMIES — ALTERING 
A  SEAMLESS  GOLD  CROWN  TO  THE  FORM  OF  A  CORRESPONDING 
NATURAL  CROWN — COMPARATIVE  MERITS  OF  THE  SECTIONAL  AND 
SEAMLESS  METHODS  OF  CONSTRUCTING  GOLD  CROWNS 

The  description  given  will  relate  to  specially  formed  seamless  gold 
crowns,  those  made  by  dies  or  in  molds,  and  to  ready-made  seamless 
gold  contour  crowns.  A 
superior  molar  will  serve  as  a 
typical  case  to  illustrate  the 
process  of  adjustment.  The 
crown  or  root  is  one  that  has 
been  shaped  and  is  straight  or 
tapering  sHghtly  on  its  sides 
toward  the  occlusal  surface. 
A  crown  of  the  proper  size  is 
specially  made,  or  selected 
from  ready-made  stock.  If  the 
latter,  its  selection  will  be 
facilitated  by  having  a  plaster 
model  of  the  case  and  a  wire 
measurement  of  the  neck. 
The  crown  is  annealed,  slipped  over  the  end  of  the  root  or  tooth  and 
gently  worked  upward;  the  gold  of  the  collar  will  partly  adapt  itself 
to  the  form  of  the  root  in  the  operation  until  the  edge  meets  the 
margin  of  the  gum  (AA,  Fig.  377). 

1.  Mark  a  line  (B)  on  the  gold  parallel  with  the  margin  of  the  gum. 

2.  Remove  and  trim  to  this  line  (A A,  Fig.  378).     If  necessary  re- 

203 


Fig.  379. 


Pig.  380. 


204 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


peat  the  marking  and  trimming  until  the  edge  meets  the  gum  evenly. 
3.  Bevel  the  edge  of  the  gold,  readjust  the  crown  and  press  it  up 
until  the  edge  of  the  collar  passes  under  the  margin  of  the  gum  and,  if 
the  occlusion  is  correct,  burnish  the  gold  to  the  cervix  (Fig.  379). 


Fig.  381. 

Expansion  of  the  Collar  and  Crown. — If  the  collar  for  the  crown  needs 
a  slight  enlargement,  it  is  easily  and  most  properly  accomplished  with 
crown  expanders  (shown  in  miniature  in  Fig.  380),  the  points  of  which 
should  be  introduced  at  first  just  within  the  edge  of  the  neck,  and  the 
gold  spread  sufficiently  to  allow  it  to  fit  over  the  end 
of  the  natural  crown  or  root  or  its  model,  the  process 
of  expansion  being  gradually  continued  as  the  crown 
is  brought  into  position.  By  proceeding  in  this 
manner  too  great  expansion  is  avoided. 

Alteration  of  a  Side 
or  Part  of  a  Crown. — 
The  contour  of  one  or 
both  sides  can  be  de- 
pressed and  the  crown 
thus  narrowed  by  intro- 
ducing the  points  of  a 
crown  expander,  or  some 
tool  that  will  fit  loosely 
inside  the  crown,  then 
steadying  the  crown  with 
the  fingers,  as  shown  in  Fig.  381,  and  tapping  the  side  to  be  reduced 
with  the  flat  end  of  a  riveting  hammer.  Pliers  will  also  accompHsh  it, 
one  beak  being  placed  inside  the  crown  and  the  other  ■  against  the 
bulge  on  the  outside  (Fig.  382).  This  is  necessary  when  the  side  of 
the  crown  presses  on  an  adjoining  tooth  and  the  crown  is  thus  pre- 
vented from  coming  into  proper  position. 

Alteration  of  the  Occlusal  Surface.— Before  the  crown  is  pressed  up 
to  its  apparently  proper  position,  the  occlusion  should  be  examined 


Pig.  382. 


Fig.  383. 


ADJUSTMENT  OF  SEAMLESS  GOLD  CROWNS 


205 


and  calculations  carefully  made  to  obviate  any  defects  of  articulation, 
which  may  be  corrected  at  this  stage  by  proper  manipulation  of  the 
crown.  Place  the  crown  in  position  on  the  tooth  and  flatten  the  interfer- 
ing part  with  a  large  gold  foil  condenser,  tapped  with  a  mallet,  or  hold  the 
crown  and  tap  the  part,  as  shown  in  Fig.  383.  The  closing  of  the  antag- 
onizing teeth  with  force  upon  the  crown  by  the  patient,  will  aid  or 
complete  the  operation  of  articulating. 

To  Deepen  the  Cusps. — Trim  a  piece  of  wood  to  the  form  shown  in 
Fig.  384,  rest  the  neck  of  the  crown  on  a  folded  napkin  and  press  the 
wood  between  the  cusps. 

To  Point,  Lengthen  or  Narrow  the  Buccal  Cusp  in  Appearance. — To 
so  change  the  buccal  cusp  of  an  upper  bicuspid  crown,  gently  tap  the 
gold  on  each  side  of  the  cusp  toward  the  point  at  the  angle  shown  in 
Fig.  385- 


Pig.  384. 


Fig.  385. 


Fig.  zi 


To  lessen  or  remove  indentations  between  cusps,  and  flatten  the  entire 
grinding-surface,  introduce  inside  the  crown  a  flat-ended  piece  of  wood 
the  size  of  the  crown  and  press  downward,  as  shown  in  Fig.  386. 

Strengthening  and  Reinforcement  of  Seamless  Gold  Crowns. 
Additional  strength  and  stiffness  may  be  given  to  seamless  gold  crowns 
when  desired  in  several  ways,  by  soldering  in  an  open  flame.  The  liabil- 
ity of  melting  the  gold  which  forms  the  side  of  the  crown  in  the  opera 
tion  is  the  objection  to  the  method.  The  crown  should  be  held  in  the 
upper  section  of  the  flame,  watched  and  instantly  removed  as  soon  as 
the  solder  fuses  and  flows.  The  heat  should  be  very  gradually  and 
uniformly  applied  by  turning  and  moving  the  crown  well  up  and  down 
in  the  flame  so  that  the  gold  of  the  crown  shall  not  become  hotter  than 
the  solder.  If  this  precaution  is  not  observed,  the  solder  when  it  melt? 
is  liable  to  penetrate  the  gold  of  the  crown.  The  crown  should  be  held 
in  such  a  position  that  a  full  view  of  the  interior  is  presented  and  the 
melting  of  the  solder  rendered  visible,  which  will  occur  at  a  red  heat. 

To  Stijffen  the  Entire  Interior  of  the  Crown. — After  it  has  been  prop- 
erly adjusted,  dampen  the  inner  surface  with  wet  cotton  on  the  point  of 


2o6  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

an  instrument,  place  in  the  interior  a  quantity  of  dry  fluxed  solder  filings, 
place  the  finger  over  the  neck  of  the  crown,  invert  and  shake  well.  A 
portion  of  the  solder  filings  will  adhere  evenly  all  over  the  wet  surface. 
The  finger  is  then  removed  and  the  surplus  dropped  back  into  the  bot- 
tle. Catch  the  edge  of  the  neck  with  tweezers  and  heat  the  crown  in  a 
large  Bunsen  flame  until  the  solder  fuses,  when  it  will  flow  evenly  over 
the  surface  of  the  gold  without  materially  altering  the  general  form. 

The  occlusal  surface  of  seamless  crowns  can  be  thickened  by  filling  the 
interior  of  the  cusps  with  solder.  If  considerable  of  the  natural  crown 
is  present,  the  solder  should  be  confined  to  the  cusps,  avoiding  all 
excess,  which  would  be  liable  to  obstruct  the  readjustment  of  the  crown, 
a  difficulty  which  often  occurs  and  is  troublesome  to  correct. 

Method  of  Forming  a  Solid  Occlusal  Surface. — An  occlusal  surface 
of  solid  gold  which  will  be  uniform  in  shape  with  that  of  the  natural 
crown  it  is  to  cap,  and  not  liable  to  interfere  with  the  readjustment,  may 
be  formed  as  follows:     Dry  the  gold  crown  and  place  in  the  interior  of 
the  grin  ding-surface  a  layer  of  Corona  gold.     Insert  the  crown,  press  to 
position  and  occlude  the  teeth  and  remove  the  crown. 
The  Corona  gold  will  exhibit  an  impression  of  the  tooth. 
Add  more  to  it  until  a  nearly  condensed  lining  of  it  fills 
the  occlusal  surface.     Now,  slightly  depress  this  lining 
with  an  oval-shaped  condenser  to  gain  space,  and  satu- 
rate it  with  solder.     This  is  done  by  applying  and  fusing 
the  solder  cut  in  very  small  pieces,  or  fluxed  solder 
filings,  on  the  surface   of  the  gold,  a  very  little  at  a  time  and  in 
quantity  only  as  much  as  the  Corona  will  absorb.     If  more  is  applied 
the  adjustment  of  the  crown  is  liable  to  be  obstructed.     If  the  opera- 
tion is  properly  performed,  it  will  result  in  an  interior  of  gold  that  will 
correspond  in  form  with  that  of  the  natural  tooth.     Another  method 
is  to  cut  a  disk  of  ^^looo  platinum  foil  the  size  of  the  interior  of  the 
occlusal  surface.     Punch  four  or  five  holes  in  the  foil  with  a  punch 
forceps  and  place  the  disk  in  position  in  the  interior  of  the  cap  over 
the  Corona  gold.     Adjust  the  crown  and  occlude  the  teeth;  remove, 
place  solder  in  small  pieces  with  flux  on  the  disk  and  heat  crown. 
The  solder  will  flow  through  the  holes  and  confine  itself  entirely  to  the 
other  or  inner  side  of  the  disk  (Fig.  387). 

External  Reinforcement  with  Platinum  and  Gold  in  "Close" 
Bites. — In  a  very  close  "bite,"  when  the  removal  of  only  very  little  of 
the  occluding  surface  of  the  tooth  crowned,  or  of  the  occluding  teeth,  is 
permissible,  one  or  more  layers  of  perforated  heavy  platinum  foil  of  a 
size  sufficient  to  cover  only  the  occluding  surface  may  be  pressed  or 
swaged   to    its  form  and  closely  soldered,  using  only  a  very  small 


ADJUSTMENT  OF  SEAMLESS  GOLD  CROWNS  207 

quantity  of  hard  solder.  By  this  latter  method  the  occluding  surface 
will  occupy  the  least  possible  space  and  present  a  metallic  face  that 
will  effectively  resist  attrition  for  some  time.  The  platinum  will 
absorb  enough  of  the  solder,  if  sufficient  heat  is  applied,  to  give  the 
grinding  surface  of  the  crown  a  color  resembling  that  of  clasp  gold. 
This  method  can  be  applied  to  the  occluding  lingual  surface  of  anterior 
crowns  as  well  as  to  occluding  surfaces  of  the  posterior  teeth. 

Solid  Seamless  Gold  Dummies. — Gold  seamless  crowns,  especially 
those  made  of  platinized  gold,  may  be  filled  solid  for  use  as  dummies 
in  bridge-work  by  investing  the  outside  surface  in  investment  material, 
heating  the  investment,  placing  small  pieces  of  hard  solder — one  at  a 
time — inside  the  crown  and  fusing  by  applying  the  full  flame  of  the  blow- 
pipe mostly  around  or  underneath  the  investment. 

Altering  a  Seamless  Gold  Crown  to  the  Form  of  a  Corresponding 
Natural  Crown. — Ready-made  gold  seamless  contour  crowns  frequently 
afford  the  means  of  easily  and  quickly  performing  a  crown  operation, 
especially  in  temporary  bridge  construction.  In  a  case  where  nearly 
all  the  natural  tooth  is  present  but  the  occlusal  surface  and  the  sides 
differ  in  shape  from  the  form  of  the  gold  crown  to  such  an  extent  as  to 
interfere  with  its  adjustment,  a  die  of  the  natural  crown  is  made  of 
fusible  metal  and  with  the  die  the  interior  of  the  gold  crown  is  altered 
in  shape  sufficiently  to  receive  the  natural  crown.  This  generally  can 
be  easily  done  by  resting  the  occluding  surface  of  the  gold  crown  on  a 
folded  napkin  and  gently  tapping  the  die  into  it.  By  this  means  a 
ready-made  gold  crown  may  be  quickly  altered  to  a  required  form. 

Comparative  Merits  of  the  Seamless  and  Sectional  Methods  of 
Constructing  Gold  Crowns. — The  seamless  and  sectional  crown  meth- 
ods each  posess  their  respective  advantages  for  the  accomplishment  of 
the  work  in  hand.  By  expertness  the  same  effective  result  may  be 
accomplished  with  few  exceptions  by  either  method.  The  constructive 
details  of  each  adapt  it  specially  to  certain  classes  of  work.  That 
method  should  be  applied,  therefore  which,  according  to  the  circum- 
stances affords  facilities  for  the  accomplishment  of  the  result  with 
the  least  labor.  Thus,  crowns  for  very  short  teeth  of  abnormal  oc- 
clusion; also  cases  of  abrasion  requiring  special  forms  of  incisal  and 
occlusal  surfaces  of  solid  metal  are  preferably  constructed  in  sections. 
Bicuspids  and  molars,  as  well  as  incisors  and  cuspids,  when  all  or  nearly 
all  of  the  natural  tooth  is  present  and  the  occlusion  is  normal,  may 
frequently  be  constructed  to  advantage  by  the  seamless  methods.  In 
the  construction  of  temporary  bridge- work  for  use  during  the  formation 
of  the  permanent  piece,  seamless  crowns  may  be  utilized  to  advantage, 
as  they  can  be  quickly  applied. 


CHAPTER  XIV 

CAST  GOLD  ROOT-CAPS  AND  CROWNS 

CAST    ROOT-CAP — CAST    GOLD    CROWN    WITH    PLATINUM    COLLAR — CAST 
GOLD   CROWN   ON  A  SECTIONAL  PLATINUM  OR  SEAMLESS  GOLD  CAP 

Either  root-caps  or  whole  or  partial  crowns  are  made  by  the  cast 
method. 

Cast  Root-cap. — For  cast  root-caps  the  end  of  the  root  is  prepared 
with  a  slight  bevel,  as  shown  in  Fig.  388,  so  that  in  the  finished  root- 
cap  the  cervical  edge  will  present  the  least  perceptible  line  of  union 
with  the  root  possible.  The  wax  model  of  the  cap  is  best  obtained 
by  the  indirect  method  from  an  amalgam  model  of  the  root  end.  The 
sprue  wire  is  inserted  as  shown  in  Fig.  389.  The  root-cap  should  be 
cast  of  a  gold  alloy  possessing  rigidity  and  strength.  An  alloy  of  two 
parts  of  22-carat  plate  and  one  part  of  clasp  gold  containing  about  four 
per  cent,  platinum  is  recommended. 

Cast  Gold  Crown  with  Platinum  Collar. — This  consists 
in    the   construction  of  a  cast  gold    crown    with  a  thin 

platinum  collar  forming  the 
cervical  edge.  This  thin  plat- 
inum permits  of  being  closely 
adapted  to  the  root  under  the 
gum  margin,  leaves  an  almost 
imperceptible  edge,  and  the 
platinum  surface  is  more  benign  to  the  tissues  than  gold. 

Form  a  collar  of  platinum,  gage  No.  38  to  40,  such  as  is  outlined  in 
Fig.  390,  that  fits  the  cervical  line  tightly.  Fuse  a  film  of  pure  gold 
over  the  outer  surface  of  the  platinum  fully  as  far  towards  the  cervical 
edge  as  you  desire  the  gold  to  extend.  Coat  the  inner  and  outer  sur- 
face of  the  collar  of  the  crown  with  wax,  adjust  on  the  tooth,  remove 
and  trim.  Trim  the  occlusal  edge  of  the  wax  to  the  edge  of  the  collar 
and  add  a  thick  floor  of  wax  to  form  the  cusp-cap.  Adjust  in  the 
mouth,  occlude  teeth  and  remove.  Trim  and  shape  the  wax  to  the 
required  contour  for  the  crown,  make  final  adjustment  to  determine 
accuracy,  and  remove.  With  a  slightly  heated  spatula  and  large  spoon- 
shaped  excavator  scrape  off  entirely  the  layer  of  wax  on  the  cavo  or 
inner-surface  of  the  platinum  collar.  Insert  the  sprue  wire  at  an  angle, 
as  shown  in  Fig.  391,  invest  and  cast. 

The  removal  of  the  wax  from  the  inside  of  the  collar  leaves  a  space 

208 


Pig.  388. 


Pig.  35 


Fig.  390. 


CAST  GOLD  ROOT-CAPS  AND  CROWNS 


209 


between  it  and  the  sides  of  the  tooth  except  at  the  cervical  edge.  This 
space  avoids  interference  from  contraction  of  the  cast  gold  and  gives 
a  slight  space  for  the  presence  of  cement. 

Cast  Gold  Crown  on  a  Sectional  Platinum  or  a  Seamless  Gold  Cap. 
This  method  is  generally  applied  only  to  bicuspids  and  molars.  An 
inferior  molar  will  be  taken  to  illustrate  the  method.  A  platinum 
tooth-cap  of  gage  No.  34  to  36  is  made  by  the  sectional  method,  with 
the  seams  soldered  with  pure  gold  (Fig.  392).  The  cap  should  closely 
fit  the  cervex  of  the  tooth  but  leave  a  space  at  least  one-sixteenth  of  an 
inch  between  the  floor  and  the  antagonizing  teeth.  A  seamless  cap  of 
either  platinum  or  gold  may  be  used  instead  of  the  platinum  cap 
constructed  in  sections. 

The  gold  crown  section  is  made  by  shaping  up  the  tooth  cap  with 
inlay  wax  to  the  desired  form  and  casting  it.  For  this  purpose  inlay 
wax  is  placed  on  the  tooth-cap,  the  cap  adjusted  and  pressed  to  position 
on  the  tooth  and  the  teeth  occluded.  The  tooth-cap  and  wax  are  re- 
moved, the  wax  trimmed  and  the  occlusal  surface  shaped  and  carved 


IV.  Wofx  m(Hijit 

Fig.  391.  Pig.  393.  Fig.  394. 

in  detail  (Fig.  393) .  The  wax  crown  section  is  then  chilled  and  removed 
from  the  tooth-cap,  mounted  for  casting,  as  shown  in  Fig.  394,  invested 
and  cast  of  pure  or  22-carat  gold.  The  cast  gold  crown  section  is 
fitted  on  the  tooth-cap  and  the  cavo-surface  of  the  cap  is  filled  with 
investing  material  and  the  cap  and  crown  sections  clamped.  The  two 
sections  are  then  united  by  fusing  small  pieces  of  20-carat  solder  around 
the  edge  of  the  crown  section  as  indicated  at  SS,  Fig.  393,  then  draw- 
ing the  solder  between  the  sections  by  occasionally  pointing  the  flame 
upon  the  occlusal  surface. 

Another  method  of  construction  is  to  use  a  seamless  platinum  cap 
of  gage  No.  36,  or  one  formed  in  sections  soldered  with  platinum  solder 
containing  15  per  cent,  of  platinum,  and  then  casting  the  gold  crown- 
cap  directly  on  the  tooth-cap.  The  contraction  of  the  gold  when  cast 
being  liable  to  affect  the  fit  of  the  crown  on  the  tooth,  is  the  objection 
to  this  method. 

An  amalgam  die  set  in  a  plaster  model  of  the  case  is  generally  used 
in  making  gold  crowns  by  either  of  these  methods. 


CHAPTER  XV 


VARIOUS  FORMS  OF  PORCELAIN -FACED  GOLD  CROWNS 


CUP-SHAPED     CAP- 


-THE    V-SHAPED     CAP — PARTIAL     COLLAR 
THE  LITCH   CROWN 


CROWNS- 


Several  methods  of  capping  the  end  of  the  root  are  practiced  in- 
tended to  afford  protection  against  decay  and  fracture  without  the 
use  of  a  collar. 

Cup-shaped  Cap.^ — The  surface  of  the  end  of  the  root  is  first  re- 
moved to,  or  nearly  to,  the  line  of  the  gum,  and  the  edge  of  the  end  then 
rounded  off  under  the  gum,  leaving  the  end  cone-shaped,  as  illustrated 


Fig.  395- 


Fig.  396. 


Fig.  397. 


Fig.  398. 


in  Fig.  395.  The  cap  is  made  of  a  disk  of  platinum  about  gage  No. 
30  to  34,  or  of  gold  about  gage  No.  30  to  32.  This  is  first  perforated  and 
adapted  to  the  orifice  of  the  root-canal,  which  requires  to  be  slightly 
countersunk.  The  disk  is  then  slit  at  the  center  of  the  lingual  side  and 
slightly  lapped  (A,  Fig.  396),  and  again  fitted  to  the  end  of  the  root  and 
closely  adapted  to  its  surface  and  margin,  which  the  lapping-over  slit 
easily  permits.  The  ends  are  then  united  with  the  least  possible  quantity 
of  solder.  The  edge  of  the  cap,  guided  by  several  adjustments,  is 
trimmed  even  with  the  sides  of  the  root  and  the  post  soldered  in  position. 
B,  Fig.  396,  shows  the  cup-shaped  cap  with  post  ready  for  the  adjust- 
ment of  the  porcelain  facing,  which  is  attached  in  the  usual  manner.  If 
the  edge  of  the  cap  is  removed  at  the  cervico-labial  section,  the  edge  of 
the  porcelain  facing  can  be  fitted  to  rest  on  the  surface  of  the  root  and 
take  the  place  of  the  metal. 
1  Dr.  J.  RoUo  Knapp's  method. 


VARIOUS  FORMS  OF  PORCELAl .\' -FACED  GOLD  CROWNS        211 


A  variation  of  this  method  is  to  grind  the  end  of  the  root  flat, 
then  tapper  off  the  lingual  and  approximal  sides  and  grind  the  labial 
section  in  a  slanting  plane  from  the  flat  surface  of  the  end  of  the  root  to 
and  under  the  cervico-labial  margin  of  the  gum,  as  shown  in  Fig.  397. 
The  cap  is  made  of  platinum  No.  36  gage  stamped  on  a  die  of  the  form 
of  the  root  end.^ 

The  V-Shaped  Cap.^ — This  consists  in  shaping  the  end  of  the  root 
and  plate  as  shown  in  Fig.  398.  The  slant  given  to  the  palatal  side  aids 
the  root  to  resist  force  in  a  forward  direction. 

Partial  Collar  Crowns. — The  advantage  of  a  collar  can  in  a  measure 
be  given  post-crowns  by  the  addition  of  a  partial  collar  or  metal  flange 
encircling  the  lingual  half  of  the  end  of  the  root.  For  this  purpose  the 
end  of  the  root  should  be  trimmed,  as  shown  in  Fig. 
399,  and  the  lingual  section  shaped  as  seen  at  A.^ 


Pig.  400. 


Fig.  401. 


To  form  a  partial  collar-cap  for  the  root,  make  a  collar  to  entirely 
encircle  the  prepared  root.  Trim  the  collar  level  with  the  root  end  and 
adapt  a  floor  of  gold  or  thin  platinum. 

To  confine  the  attachment  of  the  collar  with  the  solder  to  only  the 
required  lingual  and  approximal  sections  of  the  floor,  the  formation 
of  the  two  V-shaped  notches  seen  at  the  points  C,  C,  Fig.  400,  will  cut 
off  its  further  extension.  The  labial  section  of  the  collar,  being  unat- 
tached to  the  floor,  is  then  easily  removed,  leaving  the  floor  intact; 
this  though  should  not  be  done  until  the  post  has  been  fitted  and 
soldered. 

•  The  method  of  constructing  a  partial  cap-crown  described,  is  similar 
to  that  for  making  the  outer  cap  to  the  double  cap-crown  of  removable 
bridge-work,  where  a  collar  that  entirely  encircles  the  root  is  first  made 
and  the  labial  section  removed. 

The  Litch  Crown.  ^ — This  serviceable  partial  collar  crown  is  made  as 
follows:  The  end  of  the  root  is  shaped  the  same  as  shown  in  Fig.  399, 

1  Form  used  by  the  author. 

2  Dr.  F.  T.  Van  Woert's  method. 

*  Dr.  T.  F.  Chupein's  method. 

*  Dr.  W.  F.  Litch. 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


and  the  orij&ce  to  the  canal  well  countersunk.  A  post  is  fitted  to  the 
root-canal,  an  impression  taken  of  the  end  of  the  root  with  the  post  in 
position,  and  an  amalgam  die  made.  The  post  is  removed,  a  disk  of 
platinum,  gage  No.  36,  is  cut  in  oval  form  and  shaped  to  the  die  by- 
slitting  the  portion  on  the  sides  that  is  to  form  the  collar,  then  burnish- 
ing the  slit  portion  to  the  die,  mounting  the  die  in  a  swager  and  swaging 
the  cap  (Fig.  401  in  section).  The  cap  is  trimmed,  in- 
vested, and  the  slits  soldered  with  enough  pure  gold  to 
barely  unite  them.  The  cap  is  then  re-swaged  to  remedy 
any  contraction  caused  by  soldering.  The  cap  is  fi.tted  in 
the  mouth,  the  collar  trimmed  more  accurately  to  the 
festoon  of  the  gum,  the  post  inserted,  waxed  to  cap,  both 
removed,  invested  and  united  with  solder.  The  cap  and 
post  are  adjusted  in  the  mouth  and  the  platinum  removed 
at  the  cervico-labial  section  of  the  root. 

The  collar  is  then  burnished  to  the  root,  the  post  cut 
off  and  the  cap  is  ready  to  receive  the  porcelain  facing. 
When  the  porcelain  facing  is  being  fitted,  the  edge  of  the  floor  at  the 
cervico-labial  section  should  be  removed  to  permit  the  edge  of  the 
porcelain  facing  to  rest  directly  on  the  root.  Fig.  402  outlines  in 
section  the  crown  ready  for  investment. 

In  these  styles  of  crowns  the  main  part  of  the  work  may  be  done 
by  the  indirect  method  on  models,  but  the  final  adjustment  of  the 
porcelain  facing  in  the  mouth  is  advisable. 


Pig.  402. 


CHAPTER  XVI 

PORCELAIN  DETACHED -POST  COLLAR  CROWNS 

PORCELAIN  DETACHED — S.  S.  WHITE,  DAVIS,  ASH  AND  JUSTI  CROWNS — 
ATTACHMENT  OF  A  PORCELAIN  CROWN  WITH  A  METALLIC  BASE  BACK- 
ING— THE  GOSLEE  CROWN — CONSTRUCTION — DIATORIC  PORCELAIN 
TOOTH  CROWN — CAST  BASE  FOR  DETACHED-POST  CROWN — ALLOW- 
ANCE FOR  CONTRACTION 

S.  S.  White,  Davis,  Ash  and  Justi  Crowns. — Prepare  and  shape  the 
root  and  fit  a  collar  of  proper  width.  Grind  down  the  collar  even 
with  the  end  of  the  root  and  well  under  the  gingiva  at  the  cervico- 
labial  margin,  if  for  esthetic  reasons  it  is  desired  to  hide  the  collar  at 
that  point.  Fit  and  adjust  the  post  (Fig.  403);  select  an  S.  S.  White, 
Davis,  Ash  or  Justi  crown  and  grind  crown  to  fit  the  end  of  the  root 
and  the  edge  of  the  collar.  The  crown  and  post  are 
removed  and  a  disk  of  pure  gold  plate,  gage  No.  32, 
or  platinum,  gage  No.  40,  is  fitted  to  the  collar  as  a  floor 
with  a  slight  surplus  extending  over  the  edge.  The  base 
of  the  porcelain  crown  is  pressed  against  the  floor  to 
hold  the  gold  ^or  platinum  in  position  on  the  root  and 
the  surplus  edge  of  the  floor  bent  and  burnished  tight 
against  the  edge  of  the  collar.  The  collar  and  floor  are 
next  removed,  placed  together  as  defined  by  the  burnish- 
ing, and  united  by  the  least  possible  quantity  of  20- 
carat  solder.  The  surplus  edge  of  metal  around  the  collar  is  trimmed 
evenly,  the  cap  adjusted  to  position  on  the  root,  the  floor  perforated 
and  the  post  inserted  and  attached  with  wax. 

The  crown  is  next  adjusted  on  the  cap  to  define  the  proper  position 
for  the  post  in  the  crown  as  well  as  in  the  root.  Should  the  post  inter- 
fere with  proper  adjustment  of  the  crown,  the  hole  in  the  porcelain 
must  be  reamed  or  the  post  slightly  trimmed,  or  both  until  the  crown 
assumes  proper  position.  The  cap  and  post  are  then  removed^  in- 
vested and  soldered.  The  cap  is  fitted  on  the  root  and  the  crown 
adjusted.  Next  fit  the  crown  accurately  to  the  cap  by  pressing  the 
ground  base  of  the  porcelain  against  the  floor  of  the  cap  to  indicate 
where  to  trim  the  porcelain.  Repeat  until  the  entire  base  meets  the 
metallic  surface  evenly.     If  the  thickness  of  the  floor  at  the  cervico- 

213 


214 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


labial  margin  causes  the  joint  of  the  porcelain  to  show,  thin  the  surface 
of  the  floor  at  that  point.  For  this  reason  a  M 000  platinum  foil  floor 
which  can  be  reinforced  with  solder  at  the  lingual  section  when  the 
post  is  connected,  should  be  used  if  an  invisible  joint  of  the  porcelain 
is  demanded. 

Adjust  the  cap  and  post  on  the  root  and  only  cement  crown  in  position 
on  the  cap.  When  the  cement  has  set  sufficiently,  remove  cap  and  crown. 
Trim  any  cervical  overhanging  edge  of  porcelain  at  the  sides  even 
with  the  collar,  polish  and  cement  the  finished  crown  on  the  root. 
Fig.  404  shows  the  finished  S.  S.  White  crown,  and  Figs.  405  and  406 
the  Davis  crown. 

Attachment  of  Porcelain  Crown  with  a  Metallic  Base  Backing. 
This  consists  in  swaging  or  casting  a  cup-shaped  backing  or  base  to  a 
porcelain  crown  and  soldering  it  to  the  floor  of  the  root-cap.  The 
base  of  the  crown  is  ground  so  as  to  leave  a  V-shaped  space  at  the 


Pig.  404.       Pig.  405.  Fig.  406.  Pig.  407.     Pig.  408.  Pig.  409 


lingual  side.  For  a  single  incisor  or  cuspid  crown,  the  backing  is 
extended  slightly  upon  the  approximal  and  lingual  sides,  as  shown  in 
Fig.  407.  For  a  bicuspid  or  molar,  the  backing  is  brought  over  the 
sides  so  that  it  will  form  a  cup-shaped  socket  in  which  the  crown  will 
sit  and  thus  greatly  lessen  the  chances  of  its  fracture  in  use  (Fig.  408). 
To  make  an  allowance  for  the  extension  of  the  gold  backing  on  the 
sides  of  the  crown,  the  porcelain  must  be  proportionately  removed-, 
as  shown  in  Fig.  409,  so  that  the  porcelain  and  gold  when  trimmed  and 
polished  shall  present  a  uniform  surface.  When  incisors  and  cuspids 
of  this  style  are  to  be  used  as  a  bridge  abutment,  the  side  or  sides 
approximal  to  the  bridge  should  be  grooved  additionally,  as  shown  in 
Fig.  410,  to  make  room  for  a  substantial  extension  of  the  gold  in  the 
form  of  a  flange,  to  afford  an  attachment  for  the  bridge. 

To  form  the  metallic  backing,  mount  the  crown — base  up — in  a 
swager,  as  shown  in  Fig.  4J1.  Swage  a  backing  of  gold  gage  No.  35  or 
platinum  gage  No.  38  to  the  form  of  the  base.    Trim  the  backing  to 


PORCELAIN  DETACHED-POST  COLLAR  CROWNS 


215 


the  proper  size;  puncture  the  plate  over  the  hole  in  the  base  of  the 
crown  and  insert  a  post;  attach  with  wax,  remove  and  solder.  Mount 
and  adjust  the  crown  on  the  root-cap,  as  shown  in  Figs.  407  and  408; 
attach  root-cap  and  backing  with  wax,  remove  crown,  invest  cap  and 
backing  (Fig.  412)  and  fill  the  V-shaped  space  with  solder  and, 
reinforce  the  sides  of  the  backing  with  a  little  of  the  solder.  Fig.  413 
shows  a  finished  cuspid  crown  and  Fig.  414  a  bicuspid  crown.     In 


Pig.  410. 


Pig.  411. 


Pig.  412. 


Pig.  413.    Pig.  414. 


the  construction,  the  backing  can  be  cast,  but  swaging  is  the  preferable 
method. 

In  preparing  porcelain  crowns  in  any  of  these  methods,  sharp 
corners  or  edges  should  be  rounded  and  polished  to  avoid  chipping  or 
cutting  through  the  gold  in  swaging. 

The  Goslee  Crown. — This  form  of  crown  is  used  more  in  the  con- 
struction of  dummies  for  bridges  than  as  a  single  crown.     It  is  a  porce- 


Pig.  415. 

lain  crown  with  a  countersunk  base,  in  the  center  of  which  is  a  hole  for 
a  pin.  Fig.  415  illustrates  the  form  of  posterior  and  anterior  crowns. 
The  base  of  the  crown  is.  backed  and  a  pin  is  extended  from  the 
backing  into  the  hole  in  the  countersunk  base.  For  a  crowning 
operation  the  backing  is  joined  to  the  root-cap.  In  bridge  construc- 
tion the  backings  to  the  dummies  are  reinforced  and  soldered  together, 
and  the  crown  is  cemented  to  the  backing  and  pin. 

Construction. — Prepare   and   cap  the  root  the  same  as  for  the 
other  porcelain  crowns.     Select  a  Goslee  crown  that  will  require  little 


2l6  CROWN-,  BRIDGE-,  AND  PORCELAIN  WORK 

or  no  grinding,  especially  on  the  sides.  Adapt  to  the  base  a  circular 
disk  of  pure  gold  plate  gage  No.  35  in  size  much  larger  than  the  base  (Fig. 
416).  This  is  best  done  by  depressing  the  center  of  the  disk  in  the 
palm  of  the  hand,  then  placing  it  on  the  base  of  the  crown,  first  burnish- 
ing in  the  center  over  the  pin-hole  and  then  from  the  center  to  the  edge. 
When  the  base  is  outlined  (Fig,  417),  remove  the  disk  and  trim  off  the 
excess,  leaving  enough  to  fully  overlap  the  margins.  Next  place  the 
crown-cap  back  on  the  crown  and  finish  burnishing  (Fig.  418). 

This  method  is  reliable  and  quicker  than  swaging  or  casting.  Swag- 
ing may  be  resorted  to  in  some  instances,  especially  if  a  platinum  back- 
ing is  used. 

Punch  a  hole  in  the  backing,  insert  a  Goslee  post  (Fig.  419)  or 
one  made  of  clasp-metal  wire,  gage  No.  14,  attach  the  post  with  wax, 
remove  backing  and  post,  invest  and  unite  with  solder  (Fig.  420). 
The  backing  and  crown  having  been  placed  in  proper  position  on  the 


Fig.  416.  Pig.  417. — Before  Fig.  418.  Fig.  419. 

trimming. 

cap  (Fig.  421),  the  crown  backing  and  root-cap  are  attached  with  wax 
and  the  crown  is  removed  from  the  backing.  The  root-cap  and  crown 
backing  are  next  invested  and  united  with  solder.  After  dressing  the 
metal  properly  at  the  edge  of  the  porcelain,  finishing  and  cementing  the 
crown  in  the  backing,  it  appears  as  illustrated  in  Fig.  422. 

Diatoric  Porcelain  Tooth  Crown. — In  this  style  the  porcelain  section 
of  the  crown  is  formed  of  a  diatoric  tooth.  These  teeth  are  applied 
only  to  bicuspids  and  molars.  Their  use  is  generally  confined  to  lower 
teeth  and  bridge-work  in  cases  where  the  sight  of  a  gold  occluding 
surface  would  be  objectionable.  Fig.  423  outlines  the  plan  of  their 
structure.  Figs.  424  and  425  illustrate  a  backing  adjusted  to  a  dia- 
toric tooth. 

The  tooth  selected  should  fit  with  as  little  grinding  as  possible. 
When  fitted,  a  piece  of  pure  gold  gage  No.  32  is  cut  of  a  size  to  cover  the 
base  and  fit  over  the  edge  about  one-sixteenth  of  an  inch.  The  gold  is 
adapted  to  the  surface  and  pressed  into  the  depression  in  the  center. 


PORCELAIN  DETACHED-POST  COLLAR  CROWNS 


217 


The  porcelain  tooth  is  next  mounted  in  a  swager  (Fig.  426)  and  the 
gold  swaged.  If  the  gold  is  perforated  in  burnishing  and  swaging  into 
the  center  hole  B,  fill  the  perforated  depression  with  gold  foil  or  Corona 
gold,  trim  the  edges  around  the  sides  and  burnish.  Remove,  invest  and 
flow  gold  solder  into  the  depression  and  Corona  gold  and  a  little  over  the 
adjoining  surface.  Tooth  and  socket  are  mounted  with  wax  on  the  cap 
(Fig.  427)  and  pressed  to  position  in  accordance  with  the  occlusion. 
The  excess  of  wax  around  the  sides  of  the  socket  and  cap  is  trimmed  level 


Fig.  420.         Fig.  421.     Fig.  422.     Fig.  424.         Fig.  426.         Fig.  427. 

with  the  surface  of  the  gold.  The  surface  of  the  wax  on  the  sides  is 
then  covered  with  a  strip  of  No.  60  rolled  gold  or  3^^000  platinum  foil, 
leaving  the  lingual  side  open  to  act  as  a  matrix.  The  diatoric  tooth  is 
next  lifted  from  the  socket  and  the  socket  and  cap  are  invested  and 
soldered  together.  The  diatoric  tooth  is  cemented  in  the  cap.  In 
bridges  the  backings  or  bases  are  united  and  reinforced  with  solder  to 
the  line  as  indicated  at  A,  Fig.  425. 

Cast  Base  for  Detached-Post  Crowns. — When  a  cast  gold  base  is 
used  instead  of  a  swaged  base  for  any  of  the  detached-post  crowns 
described,  the  wax  model  of  the  base  should  fit  the  crown  accurately 
but  loosely.  This  slight  looseness  is  to  allow  for  contraction  of  the 
gold  in  casting. 

Allowance  for  Contraction. — For  all  styles  of  cast  backings  or  bases 
for  porcelain  crowns  or  dummies,  a  uniform  allowance  for  contraction 
in  casting  is  secured  by  giving  the  surface  of  the  porcelain  a  coat  of 
collodion  and  when  dry,  vaselining  its  surface  before  forming  the  wax 
model.  The  subsequent  removal  of  the  collodion  will  furnish  the  re- 
quired space. 


CHAPTER  XVII 

PARTIAL  CROWN-WORK 

RESTORATION  WITH  INLAYS — HISTORY — MERITS — CRITICISM — IMPAR- 
TIALLY CONSIDERED — ^PREPARATORY  TREATMENT  IN  INLAY  WORK 
— PRINCIPLES  GOVERNING  THE  PREPARATION  OE  CAVITIES — 
ANCHORAGE — PREPARATION  OF  CAVITIES — GOLD  INLAYS — ^LABIAL, 
BUCCAL  AND  OCCLUSAL  CAVITIES — APPROXIMAL  CAVITIES — COMPOUND 
CAVITIES 

Restoration  with  Inlays 

History. — The  restoration  of  decayed  teeth  by  mechanical  means 
other  than  the  use  of  various  filling  materials  packed  into  the  cavity 
dates  back  to  the  latter  part,  of  the  last  century.  Dr.  Herbst,  of 
Germany,  who  was  visiting  this  country  about  thirty  years  ago,  brought 
to  the  attention  of  the  profession  his  method  of  filling  cervical  cavities 
which  were  exposed  to  view,  with  cemented  glass  inlays  colored  to 
approximate  the  shade  of  the  teeth  so  as  to  appear  less  noticeable  than 
the  filling  materials  then  in  use. 


Pig.  428. 


Pig.  430. 


Pig.  431. 


Dr.  Herbst's  operations  drew  attention  to  inlays  as  a  method  of 
artificial  restoration  of  tooth  structure.  The  possibiHties  which  might 
be  obtained  by  such  a  method  were  an  incentive  to  the  inventive  genius 
of  members  of  the  profession,  who  have  since  gradually  brought  the 
method  to  the  prominence  it  has  now  obtained  in  dental  practice. 

Coincident  with  the  improvements  made  on  Dr.  Herbst's  early 
inlay  operations  by  the  substitution  of  low-fusing  porcelain  for  anterior 
teeth,  was  the  use  of  gold  for  the  posterior  teeth.     These  early  opera- 

218 


PARTIAL  CROWN-WORK  219 

tions  with  gold  consisted  in  swaging  or  bending  pieces  of  plate  to  the 
contour  of  the  part  of  the  tooth  to  be  restored  and  then  trimming  the 
gold  so  that  it  accurately  fitted  the  orifice  of  the  cavity.  A  pin  or 
pins  were  soldered  to  the  cavo-surface  of  the  plate  to  retain  it  in  posi- 
tion in  the  cement  or  gutta-percha  with  which  the  cavity  was  filled 
(Fig.  428).  This  style  of  restoration  was  followed  by  the  box  or  hollow 
inlay.  This  consisted  of  a  shell  of  thin  gold  plate  shaped  to  the  cavity 
like  a  matrix  with  a  hole  in  the  center  of  the  cavo-surface  (Fig.  429), 
with  plate  to  form  the  contour  soldered  over  it  and  trimmed  to  fit  the 
edge  of  the  cavity  (Fig.  430).  The  inside  of  the  box  inlay  was  filled 
with  cement  through  the  hole  in  the  cavo-surface,  the  cavity  of  the  tooth 
lined  with  cement  and   the  inlay  then   cemented   to  position  (Fig. 

431)-  .  .      ,    ,. 

The  next  advance  consisted  in  accurately  shapmg  a  matrix  of  thm 

pure  gold  plate  or  platinum  foil— generally  the  latter — to  the  exact  form 

of  the  cavity  of  the  tooth  and  filling  the  matrix  with 

gold  solder  or  plate  to  the  form  of  the  contour  of  the 

part  to  be  restored.^     Fig.  432  shows  this  method 

applied  to  a  pulpless   bicuspid.     A  globule  of   gold 

was  partly  fused  and  attached  at  the  point  A  in  the 

matrix,  and  then  gold  foil  or  crystal  gold  was  packed 

around  it  to  the  form  required,  the  inlay  invested  and 

solder  melted  into  the  foil  or  crystal  gold. 

This  latter  method,  with  improvements  respect- 
ing the  details  of  the  operation,  holds  good  at  the    ^^^^^ 
present  time  as  one  to  utilize  in  special  cases.  p^^  ^^^^ 

The  great  impetus  to  gold  inlay  work  was  the  in- 
troduction by  Dr.  Wm.  H.  Taggart,  in  1907,  of  the  method  of  casting 
inlays  from  wax  forms  or  models.  Although  the  matrix  gold  mlay 
can  be  made  by  an  expert  to  fill  the  requirements  of  an  inlay,  the 
casting  method  so  simplified  the  operation  for  the  general  practitioner 
and  shortened  it  for  the  patient  that  it  immediately  took  its  place 
as  a  preferable  method. 

Merits.— The  merits  claimed  for  inlays  in  operative  procedure  are: 

^^V,-^ —Absolute  closure  of  the  cavity  and  exclusion  of  the  oral 
secretions,  as  the  cement  lining  the  walls  of  the  cavity  in  combination 
with  the  burnished  edges  of  the  inlay— where  gold  is  used— hermetically 

seals  it. 

^ecowJ.— Complete  restoration  of  contour. 

7^;^^V^._Efficiency  and  durability  of  occlusal  surface  compared  with 
the  average  gold  filling. 

'Dr.  W.  V.  B.  Ames. 


220  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Fourth. — The  cement  lining  is  more  benign  to  the  dentin  than 
gold  and  acts  as  a  thermal  and  electric  non-conduCtor  to  protect  the 
pulp. 

Fifth. — Relieves  the  operator  of  the  tedious  and  laborious  work, 
at  times  most  exhaustive  to  himself  and  patient,  incident  to  and  con- 
nected with  the  insertion  of  large  gold  fillings. 

Sixth. — Easily  permits  restoration  with  gold,  in  many  cavities  in 
the  posterior  teeth  that  otherwise  would  be  filled  with  amalgam. 

Criticism. — The  merits  of  inlay  restoration  as  above  outlined  are 
criticised  on  the  following  points: 

First. — That  inlay  construction  and  insertion  requires  a  form  of  cavity 
which  demands  the  removal  of  tooth  structure  which  could  be  ad- 
vantageously retained  by  other  methods. 

Second. — That  in  cases  of  approximal  cavities  in  bicuspids  and  molars 
on  one  side — especially  when  both  sides  of  the  crown  are  involved — ■ 
the  buccal  and  lingual  cusps  are  weakened  by  the  extensive  removal  of 
tooth  structure  required  to  secure  a  suitable  form  of  cavity  and  a  reliable 
anchorage. 

Third. — That  the  extensive  removal  of  tooth  structure  required 
in  inlay  work  renders  many  teeth  hypersensitive  and  causes  progressive 
calcification  of  the  pulp. 

Fourth. — That  the  percentage  of  decay  which  occurs  at  the  cervical 
margins  of  inlays  is  greater  than  with  fillings. 

Fifth. — That  the  more  extensive  the  decay,  the  poorer  the  tooth 
structure  and  the  greater  the  liability  to  recurrence  of  decay, — es- 
pecially at  the  cervical  section,- — proportionately  is  an  amalgam  filling 
more  suitable  for  restorative  purposes  than  the  inlay. 

Sixth. — That  the  presence  of  dentin  and  enamel  capable  of  resisting 
decay  is  preferable  to  gold  or  porcelain;  therefore  the  requirements  in 
cavity  preparation  for  the  insertion  of  fillings  have  the  advantage  over 
inlays. 

Impartially  Considered. — Inlay-work  is  a  valuable  acquisition  to 
dental  practice.  As  a  comparative  innovation,  the  exact  sphere  of  its 
application  and  usefulness  is  not  yet  as  clearly  defined  as  it  will  be. 
The  adoption  of  inlays  in  operative  dentistry  to  the  exclusion  of  other 
methods,  wholly  or  in  part,  by  many  practitioners,  will  in  time  when 
their  merits  have  been  more  truly  tested  and  are  better  understood, 
be  modified  by  a  more  rational  interpretation. 

The  general  opinion  in  conservative  practice  seems  to  be  that  in 
the  anterior  teeth  where  the  cavities  are  so  situated  that  the  appear- 
ance of  gold  fillings  is  objectionable,  porcelain  inlays  should  be  used; 
that  gold  fillings  are  best  inserted  where  cavities  are  small  and  invisi- 


PARTIAL  CROWN-WORK  221 

ble,  but  when  such  cavities  are  large,  gold  inlays  are  preferable;  thai 
in  the  posterior  teeth  the  gold  inlay  may  be  used  when  the  cavity  re- 
specting location,  size  and  condition  suggests,  in  preference  to  the 
packed  filling. 

When  gold  is  to  be  used  as  an  artificial  restorative  agent  in  teeth 
exhibiting  a  soft  and  brittle  condition  of  the  enamel,  a  gold  inlay  can 
undoubtedly  be  more  advantageously  inserted  than  a  gold  filling,  as 
the  latter  requires  to  be  condensed  against  the  enamel  edges  of  the 
cavity  where  the  former  is  cemented.  Accordingly  suitable  cavities 
for  inlay  work  may  be  classed  as  follows: 

First. — Medium  or  large-sized  cavities  so  located  that  formerly  the 
operator  preferably  inserted  gold  fillings. 

Second. — ^Large  gold  restorations  requiring  to  be  contoured  against 
the  adjoining  teeth  to  protect  the  gum  septa,  the  forming  of  which 
with  gold  foil  would  be  very  laborious. 

Third. — Extensive  restoration  of  the  coronal  section  of  a  tooth  in 
preference  to  the  use  of  a  gold  cap. 

Fourth. — Restoration  on  an_occlusal  surface  with  gold  and  knuck- 
ling it  against  adjoining  teeth  so  as  to  leave  the  interproximal  space 
open  and  free  and  provide  room  for  the  gum  septa;  also,  incisive  edges — 
when  permissible;  and  exposed  cavities  and  fractured  portions  of  the 
front  teeth  with  porcelain. 

Cavities  unsuitable  for  inlay  work  may  be  classed  as  follows: 

First. — Cavities  so  located  respecting  position  and  decay  that  they 
are  extremely  difficult  to  effectively  treat. 

Second. — Cases  where  extensive  cervical  approximal  decay  exists, 
and  where  to  cut  parallel  walls  would  involve  the  removal  of  a  large 
quantity  of  enamel  and  dentin  that  could  be  allowed  to  remain  by 
using  a  combined  cement  and  amalgam  filHng. 

Third. — When  the  age  or  health  of  the  patient  or  the  extreme  hyper- 
sensitiveness  of  the  dentin  is  not  favorable  to  an  extensive  removal  of 
tooth  structure  such  as  the  case  would  require  for  inlay-work. 

Fourth. — When  the  condition  of  the  teeth  and  the  secretions  of  the 
mouth  are  such  as  to  suggest  a  recurrence  of  decay  as  likely  at  the  mar- 
gins of  a  filling  or  inlay  or  on  the  adjacent  surface  of  the  structure  of 
the  tooth. 

Preparatory  Treatment  in  Inlay  Work.^ — In  cases  of  approximal 
cavities,  it  is  advisable  to  pack  the  interproximal  space  previous  to  the 
operation  for  the  purpose  of  separating  the  teeth  enough  to  secure  a 
slight  additional  space,  also  to  press  up  the  gum  septum  and  expose  that 
part  of  the  cervical  section  of  the  tooth.     Some  operators  claim  that 

'  The  description  here  given  applies  closely  to  porcelain  as  well  as  gold  inlay  work. 


222 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


no  additional  space  is  required  beyond  that  obtained  by  the  necessary 
removal  of  the  contour  of  the  tooth. 

Cervico-buccal  cavities  close  to  or  extending  under  the  gingival  . 
margin  should  be  packed  with  gutta-percha  previous  to  the  operation 
to  expose  the  cervical  section.     This  is  done  by  inserting  in  the  cavity 
an   excess   of  the  gutta-percha  and  pressing  the  excess  against^^the 
gingiva. 

Desensitizing  the  cavity  is  advisable  when  conditions  suggest  it. 
Any  preferred  agent  for  th"e  purpose  may  be  inserted  in  the  cavity  when 
the  space  is  packed.  When  decay  has  closely  approached  the  pulp 
the  dentin  should  be  sterilized,  as  described  in  Part  II,  Chapter  I,  and 
the  pulpal  section  of  the  cavity  filled  with  zinc  oxyphosphate  cement. 
When  the  cement  is  set  it  is  removed  sufficiently  to  give  proper  form 
to  the  cavity  for  the  inlay. 

Principles  Governing  the  Preparation  of  Cavities 

The  principles  governing  the  preparation  of  cavities  for  gold  and 
porcelain  inlays  are  generally  the  same.  The  floor  or  pulpal  wall  is 
shaped  as  flat  as  the  form  of  the  teeth  will  permit  without  encroaching 
on  the  area  of  the  pulp.  The  side  walls  are  trimmed  so  that  their 
junction  with  the  floor  forms  a  slightly  obtuse  angle.     The  line  of  the 


Pig.  433. 


Pig.  434. 


Pig.  435. 


Pig.  436. 


side  walls  should  be  placed  as  nearly  as  possible  parallel  with  that  of 
the  enamel  rods.  Fig.  433  shows  the  correct  and  Fig.  434  the  incorrect 
form.  A  very  slight  bevel  at  the  edge  of  the  enamel  is  advocated  for 
gold,  as  it  is  more  effectively  burnished  against  a  beveled  than  a  straight 
margin.  For  porcelain  inlays  the  edge  should  be  square  to  avoid  a 
fragile  thin  edge  on  the  inlay.  There  should  be  no  undercuts.  The 
cavity  should  be  of  sufficient  depth  to  afford  retention  for  the  inlay. 
The  form  given  should  allow  insertion  and  withdrawal  of  a  wax  model 
of  the  cavity  or  a  metaUic  matrix  in  a  direct  line  with  the  walls  of  the 
cavity. 

Anchorage. — An  inlay  that  is  not  anchored  is  entirely  retained  by 
the  cement.     Inlays  in  labial  and  buccal  surfaces,  also  positions  where 


PA  RTIA  L  CROWN -WORK 


2  2.3 


no  force  is  exerted  to  dislodge  them  and  iij  occlusal  cavities  where  the 
force  is  direct  can  generally  be  retained  by  the  cement  alone.  Con- 
toured inlays  in  positions  where  a  leverage  or  lateral  pressure  is  exerted 
in  occlusion  and  mastication  are  liable  to  be  dislodged  unless  anchored 
by  being  compound-mortised  or  locked  in  the  adjoining  tooth  struc- 
ture. Inlays  used  as  abutments  for  bridge-work  require  to  be  so 
anchored.  The  principle  of  the  mortise  as  a  mechanical  device  is 
illustrated  in  Fig.  435,  which  shows  the  simple  form  and  in  Fig.  436, 
a  compound  mortise.  This  principle  of  anchoring  inlays  is  practiced 
in  all  operations  in  which  they  are  required  to  withstand  force  that  other- 
wise might  loosen  them,  and  especially  where  they  are  used  as  a  support 
in  bridge-work. 

Preparation  of  Cavities 

In  the  preparation  of  a  cavity,  first,  with  a  sharp,  suitably  shaped 
chisel  cut  down  all  the  frail  enamel  wall  around  the  margins  until 
healthy    enamel   is   reached.     Next,    with   spoon-shaped    excavators 


1 


\\\ 


Fig.  437- 


remove  decayed  and  affected  dentin,  cutting  from  the  center  toward 
the  edges  as  less  painful  to  the  patient,  and  also  to  avoid  accidental 
exposure  of  the  pulp. 

The  extent  of  the  cavity  having  been  outlined  by  this  preliminary 
excavation,  sharp  rose-head  and  round  burs  may  be  used  to  remove 
remaining  affected  dentin.  Overhanging  edges  of  enamel  caused  by 
the  excavation  of  the  decayed  dentin  are  next  removed  with  suitable 
sized  cone-shape  and  fissure  burs,  finishing  with  small  round  and  taper- 
ing oblong  carborundum  points  (Fig.  437).  Towards  and  at  the  cervi- 
cal section  of  sensitive  teeth,  the  shaping  and  finishing  should  be  done 
entirely  with  carborundum  points,  using  first  coarse  and  then  fine.  They 
are  less  painful  than  burs,  trim  rapidly  and  leave  a  finished  surface. 
Carborundum  points  should  be  kept  wet  and  used  with  a  steady  hand 
in  either  the  straight  or  right-angled  handpiece.  Small  circular 
knife-edge  stones  are  useful  for  opening  fissures  or  to  assist  in  cutting 
away  a  portion  of  the  central  section  of  the  occlusal  surface  of  a  tooth 


224 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


for  the  purpose  of  forming  an  anchorage  for  an  inlay.  Oblong  taper- 
ing Arkansas-stone  points  may  be  used  for  the  final  finish  of  the  edges. 

When  the  required  form  has  apparently  been  given  the  cavity,  it 
may  be  assured  by  making  a  test.  This  is  easily  done  by  pressing  a 
piece  of  softened  base-plate  guttta-percha  into  the  wet  cavity,  chilling 
and  removing.  If  there  is  an  interference,  it  will  be  indicated  by 
resistance  in  the  act  of  removal.  An  examination  of  the  gutta-percha 
will  show  the  point  or  points  which  require  trimming. 

Gold  Inlays. — The  description  of  the  preparation  of  the  cavities 
for  gold  inlays  in  the  following  located  positions  will  largely  cover  the 
subject. 

Labial,  Buccal  and  Occlusal  Cavities. — Fig.  438  shows  a  labial 
cavity  in  a  superior  cuspid  that  extends  under  the  gingival  margin, 


Fig.  438. 


Fig.  439- 


Fig.  440. 


where  a  gold  inlay  is  frequently  inserted  in  preference  to  porcelain, 
especially  when  the  lip  does  not  expose  it. 

Fig.  439  shows  a  cavity  of  the  same  class  prepared  in  an  inferior 
bicuspid. 

Approximal  Cavities. — Fig.  440  shows  an  approximal  prepared 
cavity  in  a  left  central  incisor.  Viewed  from  the  lingual  side  (A)  two 
square  corners  are  seen  formed  for  retention.  In  the  cuspid  shown  in 
Fig.  441  the  contour  required  to  be  given  the  inlay  calls  for  a  more 
extensive  anchorage.  These  inlays  are  inserted  laterally.  Fig.  442 
shows  a  prepared  cavity  in  a  left  central  incisor  that  involves  a  portion 
of  the  incisal  edge.  A  is  the  labial  and  B  the  lingual  side.  The  dotted 
line  indicates  the  form  of  the  cavity. 

Fig.  443  is  typical  ofi^the  formation  of  an  approximal  cavity  in  a 
molar.  In  this  class  of  cavities  in  bicuspids  and  molars,  likewise 
cavities  in  all  teeth  where  the  inlay  has  to  be  inserted  in  an  occlusal 
direction,  the  approximal  side  should  be  cut  straight  from  the  occlusal 


PA RTIAL  CROWN-WORK 


225 


surface  to  the  line  of  the  cervical  edge  of  the  cavity,  and  then  given  a  very 
slight  outward  flare.  Attention  is  called  to  the  anchorage  made  in  the 
occlusal  surface  with  straight  walls  at  a  slightly  obtuse  angle  to  the 
floor  or  pulpal  wall;  also  the  level  cervical 
wall  slightly  rounded  at  the  corners.  This 
latter  mentioned  cervical  section,  termed  the 
"step,"  is  extended  under  the  free  margin  of 
A  B 


Fig.  441. 


Pig.  442. 


Pig.  443. 


the  gum  for  the  purpose  of  substituting  tooth  structure  with  the  inlay, 
and  thus  more  effectively  resisting  the  recurrence  of  decay.  This 
method  of  preparing  a  cavity  is  what  in  dental  parlance  is  now 
termed  "Extension  for  Prevention." 
It  is,  however,  only  the  principle  prac- 
ticed and  advocated  in  the  past  in  a 
conservative  way  by  experienced  opera- 
tors. It  is  not  advisable  to  practice 
this  method  in  an  extreme  manner,  as, 
where  strong,  sound  dentin  is  present 
and  apparently  more  than  average  im- 
munity to  future  decay  of  the  teeth; 
nor  in  the  case  of  nervous  patients  with 
teeth  extremely  sensitive  to  excavation 
of  the  dentin  and  to  thermal  changes. 
Fig.  444  illustrates  in  section  the  "step  " 
and  also  a  groove  or  anchorage  that 
may,  when  conditions  suggest  it,  be 
added  as  an  anchorage  lug. 

Fig.  445  shows  the  form  of  an  inlay 
in  the  approximal  side  of  a  bicuspid.  The  cavity  in  the  occlusal  sur- 
face was  shaped  oval  instead  of  square  as  in  the  molar,  to  lock  or 
anchor  the  approximal  section.     In  many  cases,  oval-shaped  anchor- 

15 


Fig.  446. 


Pig.  445. 


226 


CROWN-    BRIDGE-,  AND  PORCELAIN-WORK 


age  cavities  are  preferable  to  the  square.     Fig.  446  shows  a  method 

of  anchoring  an  inlay  with  notches  ground  in  the  sides  of  the  cavity. 

In  occlusal  cavities  in  bicuspids  and  molars  where  the  decay  has 

involved  the  surrounding  walls  extensively,  they  should 

be  ground  down,  as  shown  in  Fig.  447,  and  the  entire 

occlusal  surface  reproduced  in  gold. 


Fig.  447. 


Fig.  448. 


Fig,  449. 


Compound  Cavities. — Fig.  448  shows  a  prepared  compound  cavity 
that  involves  both  approximal  surfaces  and  unites  them  by  extension 


Fig.  450. 

through   the   occlusal  surface.     By  this  plan  one  mlay  anchors   the 
other.     In  such  cases,  the  axial  walls  must  slightly  converge  toward 


Fig.  451. 


the  occlusal  surface  to  admit  withdrawal  of  the  wax  without  change  of 
form.     If  the  form  of  the  tooth  will  not  properly  permit  the  formation 


PARTIAL  CROWN-WORK 


227 


of  the  two  inlays  as  one,  they  can  be  made  separately  to  meet  and  lock 
in  the  center  of  the  occlusal  surface. 

In  most  of  these  cases  it  is  advisable  to  grind  down  the  cusps  and 
occlusal  surface  and  reproduce  them  in  gold,  as  shown  in  Fig.  449,  a 
bicuspid,  and  Fig.  450,  a  molar.     When  this  is  not  done,    slanting 


Fig.  452. 

fracture  of  the  buccal  or  lingual  section  of  the  tooth  is  liable  to  occur, 
owing  to  removal  of  the  dentin  and  enamel  intervening  between  and 
connecting  the  cusps. 

Fig.  451  is  a  central  incisor  in  which  the  approximal,  a  portion  of  the 
lingual  and  labial  sides  and  the  entire  incisive  edge  are  reproduced  in 
gold.  Fig.  452  is  a  cuspid  treated  in  the  same  manner.  In  these  cases 
the  inlay  is  inserted  in  an  incisal  direction. 


CHAPTER  XVIII 

PAPTIAL  CROWN-WORK,  CONTINUED 

GOLD  INLAY  FORMATION — DIRECT  METHOD — PIN  ANCHORAGE  FOR  GOLD 
INLAYS — HOLLOWING  OF  GOLD  INLAYS — MATRIX  GOLD  INLAYS — 
PROCESS  OF  FORMATION — SOLID  GOLD  TIPS  FOR  ABRADED  PULPLESS 
ANTERIOR  TEETH — THE  CASTING    METHOD — CASES    OF  VITAL    PULPS 

Gold  Inlay  Formation. — A  gold  inlay  is  made  by  casting  in  the  mold 
of  a  wax  model  of  the  cavity,  or  by  fusing  the  metal  in  a  platinum  or 
gold  matrix.  The  wax  model  or  matrix  is  shaped  either  directly  in 
the  cavity  of  the  tooth  in  the  mouth  or  indirectly  in  a  model  of  the 
cavity  from  an  impression.  The  former  is  called  the  Direct  Method, 
the  latter  the  Indirect.     (See  The  Casting  Process,  Part  I,  Chapter  VI.) 

Direct  Method. — The  model  is  made  of  inlay  wax  which  is  formed 


Pig.  453. 

in  conveniently  shaped  pieces  of  different  sizes,  such  as  are  shown  in 
Fig.  453.  Place  a  piece  in  warm  water,  not  over  140°  F.,  until  it  is 
thoroughly  softened.  Dry  heat  is  not  suitable.  The  wax  may  be 
slightly  pressed  between  the  fingers  to  give  it  form  but  it  should  not 
be  manipulated.  The  suitable  shaped  end  of  the  piece  of  wax— which 
should  be  smaller  than  the  orifice — is  placed  in  the  cavity  and  the  mass 
pressed  with  the  fingers  so  that  the  wax  will  be  forced  against  all  the 
walls  and  exude  outside.  Let  the  wax  cool  slightly,  partly  trim  off  the 
surplus,  then  soften  the  occlusal  surface  with  a  heated  spatula  and  in- 
struct the  patient  to  occlude  the  teeth,  first  directly  and  then  make  the 
lateral  movements. 

The  wax  is  shaped  to  the  required  form  with  a  warm  spatula.  Trim 
from  the  center  toward  the  margin  to  avoid  disturbing  the  adaptation 
of  the  wax  to  the  edge  of  the  cavity.  The  approximal  side,  especially 
at  the  cervical  edge,  may  be  smoothed  by  drawing  across  the  surface 
a  strip  of  thin  celluloid  or  silk  tape,  imperceptibly  coated  with  glycer- 

228 


PARTIAL  CROWN -WORK 


229 


in.  On  the  occlusal  surface  and  sides  a  pellet  of  cotton  twisted  on  the 
end  of  an  instrument  and  slightly  moistened  with  glycerin,  should  be 
applied  to  smooth  the  occlusal  surface  and  exposed  sides. 

As  the  wax  model  will  be  accurately  reproduced  in  every  detail  in 
gold,  the  wax  should  be  trimmed  to  the  exact  form  required  and  im- 
perfections or  any  excess  avoided  as  it  is  much  easier  to  trim  the  wax 
than  the  gold.     The  warmth  of  the  mouth  keeps  the  wax  moderately 


Fig.  45  4. 


Fig.  455- 


soft.     When  properly  shaped  the  wax  is  chilled  with  a  stream  of  cold 
water  and  carefully  lifted  from  the  cavity  without  change  of  form. 

When  necessary  to  remove  the  wax  model  from  the  cavity  to  trim, 
it  should  be  placed  again  in  warm  water  to  soften  the  wax  before  re- 
placement in  the  cavity. 

The  finished  wax  model  is  Hf ted  from  the  cavity  with  a  small  pointed 
instrument.  A  sprue  wire  is  heated  and  the  extreme  point  thinly  veneer- 
ed with  an  atom  of  adhesive  wax.  The  wax  inlay 
is  held  between  the  fingers  of  the  left  hand  and 
the  point  of  the  sprue  wire  introduced  into  the 
most  suitable  part  of  either  the  occlusal  or  approxi- 
mal  surface  (Fig.  454). 

The  inlay  on  the  sprue  wire  is  next  mounted  in 
the  circular  plate  of  the  casting  flask  (Fig.  455) 
and  the  flask  ring  set  around  it.  Investment 
material  is  mixed  and  the  inlay  invested  and 
cast,  as  described  in  Casting,  Part  I,  Chapter 
VII. 

An  inlay  inserted  in  the  occlusal  and  mesial  or 
distal  side  of  a  tooth  is  termed  respectively  an  MO  or  DO  inlay  and 
when  on  both  sides  and  occlusal  surface  MOD  inlay. 

Pin  Anchorage  for  Gold  Inlays.— When  an  inlay  is  contoured  and 
the  stress  of  occlusion  is  liable  to  cause  its  displacement,  a  pin  or  pins 
ought  to  be  inserted  in  the  dentin  from  the  inlay  at  the  side  opposite 
the  contour  to  counteract  the  leverage.  Such  an  anchorage  is  also 
advisable  when  an  inlay  is  used  as  an  attachment  for  a  bridge  (Fig. 
456).     See  Part  IV  Chapter  IV. 


Fig.  456. 


230 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Hollowing  of  Gold  Inlays. — Large  inlays  may  be  advantageously 
hollowed  out  from  the  direction  of  the  pulpal  wall  or  floor.  This  re- 
duces their  weight  and  expense,  also  aids  their  retention  by  the  forma- 
tion of  a  large  undercut.  The  wax  is  removed  from  the  center  of  the 
inlay,  avoiding  distortion,  with  a  small  hollow  tube,  the  end  of  which  is 
heated,  introduced  into  the  wax  and  the  melted  wax  drawn  out  into  a 


Fig.  457. 

chamber  filled  with  cotton  by  sucking  on  the  tube.     Fig.  457  is  Roach's 
instrument  for  this  purpose. 

Fig.  458  illustrates  an  instrument  termed  a  vacuum  wax  carver.' 
It  is  to  be  placed  on  the  point  of  an  electric  hot-air  syringe  and  will 
melt  and  effectually  suck  out  any  quantity  of  wax.  A,  in  section,  illus- 
trates the  construction,  and  B,  the  actual  size  of  the  instrument. 
A  wax  inlay  may  also  be  hollowed  by  introducing  the  heated  point  of 


<  ^^< 


Pig.  458. 

an  instrument  into  the  part  to  be  removed,  withdrawing  the  instrument, 
wiping  off  the  point  and  reintroducing  it  several  times,  but  this  is  a 
slow  method  and  liable  to  soften  and  distort  the  wax. 

Matrix  Gold  Inlays 

The  use  of  the  matrix  method  of  constructing  a  gold  inlay,  which 
preceded  in  practice  the  cast  form,  is  at  present  mostly  confined  to 
cases  for  which  it  has  special  merit.     Such  cases  are  anchorage  inlays, 

1  Manufactured  by  the  Electro-Dental  Mfg.  Co. 


PARTIAL  CROWN -WORK  23 1 

incisal  tips  and  small  corners  on  the  front  teeth,  small  and  moderately 
large  occlusal  cavities  in  bicuspids  and  molars;  also  many  cervical  and 
buccal  cavities,  and,  in  fact,  many  cavities  requiring  little  or  no 
contour. 

One  of  the  advantages  of  the  method  over  casting  for  many  simple 
cavities  is  that  one  expert  in  matrix  formation  can  occasionally  make 
and  insert  an  inlay  immediately  in  a  fraction  of  the  time  required  for 
a  casting  operation.  Another  is  that  where  the  inlay  is  intended  to. 
assist  in  retarding  the  wearing  away  process  termed  attrition,  in  cases 
of  mechanical  abrasion,  the  inlay  or  tip  can  be  conveniently  made  of 
the  hardest  of  the  alloys  of  gold,  such  as  clasp  gold  or  some  other  hard 
alloy. 

Process  of  Formation,  ^ — The  cavity  is  prepared  in  the  same  manner 
as  in  the  casting  method.  The  matrix  is  made  of  Kooo  gage  platinum. 
.Either  Kooo  Pure  gold  or  2  to  3  per  cent,  platinized  gold  may  also 
be  used.  Preference  is  given  to  the  platinum  because  it  is  more  rigid 
than  gold  when  adapted  and  is  not  so  liable  to  be  melted  in  any  process 
connected  with  the  work  and  therefore  does  not  necessarily  always 
require  investment.  It  is  not  as  easily  adapted  to  the  cavity  as  gold, 
but  folds  of  the  foil  on  the  cavo-surface  of  the  matrix  not  located  at  the 
edge  are  not  material,  as  all  will  be  united  by  the  gold  and  become  part 
of  the  inlay. 

Ample  spaces  between  teeth  obtained  prior  to  the  operation  and 
exposure  of  the  cervical  margins  of  cavities  are  as  necessary  as  in  the 
casting  method. 

A  piece  of  Hooo  inch  platinum  foil  which  has  been  annealed  in  an 
electric  furnace,  at  not  less  than  2200°  F.,  is  cut  sufficiently  large  to 
cover  the  cavity  and  extend  beyond  it,  so  that  the  surplus  can  be  held 
by  the  fingers  on  the  sides  of  the  tooth  or  surfaces  of  those  adjoining. 
Place  the  foil  over  the  cavity  and  with  a  ball  of  cotton,  spunk  or  a 
soft-rubber  point  press  the  foil  down  into  the  cavity  to  define  its  posi- 
tion. While  the  surplus  is  held  securely  with  the  fingers,  next  remove 
the  cotton  or  spunk  and  by  rotating  various  sized  ball-pointed  burnish- 
ers on  the  platinum  gradually  bring  it  down  to  the  bottom  and  sides  of 
the  cavity.  In  the  operation  the  foil  may  be  cracked,  but  if  the  cracks 
are  small  and  do  not  extend  to  the  edges  of  the  cavity,  they  will  be 
bridged  over  by  the  gold  and  will  not  affect  the  inlay. 

When  the  matrix  is  adapted  and  in  the  cavity,  pack  in  sufficient 

Corona  gold  or  foil  to  cover  the  floor  and  fill  or  nearly  fill  the  matrix, 

as  already  described  and  illustrated  in  Fig.  432.     The  gold  aids  in  re- 

1  A  description  with  illustrations  of  matrix  formation  for  porcelain  inlays,  with 

which  that  for  gold  inlays  is  identical,  will  be  found  in  Part  VI,  Chapter  VI. 


232  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

taining  the  form  of  the  matrix  when  removed,  and  in  carrying  the  fused 
gold  over  any  cracks  or  imperfections  present  in  the  platinum.  The 
matrix  is  removed  from  the  mouth,  laid  on  a  soldering  block  and  a  few 
small  pieces  of  20-carat  gold  solder  or  plate  are  carefully  melted  into 
the  matrix  with  a  blowpipe  flame  so  that  it  will  be  absorbed  by  the 
Corona  gold  or  foil  and  only  reach  the  matrix  walls. 

The  matrix  is  again  adjusted  in  the  cavity  and  very  accurately 
burnished  to  the  margins.  To  the  gold  already  attached  enough  foil  or 
Corona  gold  is  added  to  fill  the  cavity  and' shape  it  to  the  desired  form. 
The  matrix  is  again  removed  and  the  cavo-surface  given  a  coat 
of  moistened  rouge  and  invested,  leaving  the  occlusal  surface  exposed 
but  the  edge  of  the  matrix  covered.  More  solder — a  little  at  a  time — is 
fused  by  degrees  on  the  surface  of  the  gold  already  in  the  matrix  in 
quantity  only  sufficient  to  properly  form  the  inlay,  as  an  excess  necessi- 
tates its  removal. 

After  soldering,  adjust  in  the  mouth  and,  should  any  point  require 
additional  gold  or  shght  shaping,  again  add  Corona  gold  and  solder. 
When  formed,  boil  in  acid,  cut  away  surplus  matrix,  do  any  necessary 
finishing  and  cement  in  the  cavity. 

Solid  Gold  Tips  for  Abraded  Pulpless  Anterior  Teeth. — These  are 
usually  made  for  cases  of  mechanical  abrasion  not  suitable  for  porce- 
lain, and  when  the  appearance  of  gold  will  not  be  objectionable  to  the 
patient. 

Solid  gold  tips  for  abraded  pulpless  anterior  teeth  are  constructed 
in  the  following  manner:  An  opening  is  made  through  the  occlusal  sur- 
face of  the  crown  into  the  root-canal.  A  flat  post  is  formed  wide 
enough  to  fit  closely  in  the  pulp-chamber  across  its  greatest  diameter, 
thus  tending  to  prevent  any  rotary  motion  of  the  gold  tip.  A  piece 
of  pure  gold  plate,  about  gage  No.  30  to  32,  is  adapted  and  burnished, 
with  hand  burnishers  and  steel  or  Herbst  revolving  agate  points,  into 
all  the  irregularities  of  the  abraded  surface  and  the  orifice  of  the  pulp- 
chamber.  The  gold  is  next  trimmed  flush  and  even  to  the  edges  and 
burnished  just  over  them.  An  opening  is  made  in  the  gold  plate  and 
the  post  inserted  through  it  in  position,  fastened  with  wax,  removed 
and  soldered  to  the  plate.  The  post  and  plate  are  inserted  in  position, 
and  the  end  of  the  post  cut  off  to  the  exact  length  the  gold  tip  requires 
to  be,  and  the  gold  again  burnished  to  the  edges  of  the  tooth  and  trim- 
med closely  (Fig.  459).  The  end  of  the  post  defines  the  length  and 
takes  the  form  of  a  hard  plug  in  the  center  of  the  finished  inlay. 

Wax  cement  is  placed  on  the  gold  and  shaped  to  the  exact  form  of 
the  required  gold  tip  (Fig.  460).  The  sides  of  the  wax  model  are  next 
encircled  with  a  strip  of  3^^000  platinum  or  No.  60  gold  foil  adapted  to 


PARTIAL  CROWN-WORK 


233 


the  surface  of  the  wax.     This  foil  strip  is  to  form  a  matrix.     All  parts 
are  now  removed  and  invested  (Fig.  461). 

The  investment  is  next  heated  and  20-carat  gold  solder  melted  into 
the  matrix  formed  by  the  foil  encircling  the  plate,  through  the  open 
incisal  edge.  The  surplus  gold  at  the  sides  is  trimmed  to  the  surface 
of  the  tooth  and  the  desired  form  of  the  tip,  and  polished.  Platinum 
foil,  when  used,  becomes  invisible  when  the  surplus  is  removed  in  the 


en:. 


Pig.  459.  Pig,  460.        Pig.  461.  Pig.  462. 


Pig.  463. 


finishing.  The  trimming  or  polishing  of  that  part  of  the  tip  adjacent 
to  or  fitting  against  the  incisal  portion  of  the  tooth  should  always  be 
done  with  the  tip  in  position  on  the  tooth.  The  gold  tip  when  finished, 
is  cemented  with  a  thin  mixture  of  oxyphosphate  cement.  Fig.  462 
gives  a  sectional  view  of  a  central  incisor  tipped  in  this  manner. 

The  Casting  Method. — Inlay  wax  is  placed  on  the  end  of  the  fitted 
pin,  the  pin  is  adjusted  to  position  in  the  tooth,  the  wax  pressed  against 
the  abraded  surface  and  shaped  to  the  form  of  the 
tip.  It  is  then  removed,  invested  and  cast.  Fig. 
463  shows  the  tip  ready  for  investment. 

Cases  of  Vital  Pulps. — In  these  cases  two  or 
three  small  platinum  pins,  gage  No.  20  or  21,  as 
the  case  may  suggest,  are  used  in  holes  drilled 
around  the  pulp-chamber  in  the  manner  shown  in 
Fig.  464.  Three  pins  should  always  be  used  except 
in  very  small  lower  incisors  where  the  space  will 
not  permit  more  than  twc>.  The  pins  should  be 
inserted  and  soldered  one  at  a  time  in  the  gold 
or  platinum  plate  which  has  been  fitted  to  the  abraded  incisal  surface 
of  the  tooth,  the  plate  being  readapted  each  time.  Tht  first  pin,  if 
fitted  tightly  in  the  hole  through  the  plate,  may  be  soldered  without 
investing,  but  an  investment  should  be  made  for  the  soldering  of 
each  subsequent  pin,  as  otherwise  the  previously  soldered  pin  or  pins 
are  liable  to  be  moved  from  correct  position.  The  least  possible 
quantity  of  solder  should  be  used  on  the  first  two  pins.  After  all  the 
pins  have  been  soldered  in  position  in  the  plate,  it  is  adjusted  on  the 


Pig.  464. 


234 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


tooth  and  the  gold  very  carefully  burnished  with  revolving  burnishers 
to  its  surface,  trimmed,  and  the  ends  of  the  pins  cut  off  so  that  they 
just  touch  the  antagonizing  teeth  when  occluded.  The  floor  is  next 
shaped  up  with  wax  and  a  matrix  formed,  as  previously  described, 
invested  and  the  matrix  filled  with  solder.  The  gold  tip  is  then 
finished  and  cemented. 

In  a  case  with  a  vital  pulp  or  in  a  pulpless  tooth,  if  the  gold  tip 
required  is  very  short,  the  ends  of  the  pins  extending  above  the  plate 
will  hold  and  maintain  enough  solder  in  position  to  furnish  material 
for  proper  contouring  without  enveloping  the  wax  model  with  a  matrix 
of  gold  or  platinum  foil. 

Another  method^  of  building  the  tip  to  any  required  length  is: 
Having  made  and  invested  the  plate  with  the  three  pins  for  the  abraded 
surface  of  the  tooth  (A,  Fig.  465),  roll  down  a  piece  of  solder  very  thin. 


Fig.  465. 


Fig.  466. 


Pig.  467. 


about  gage  No.  t,t,  to  34,  cut  it  to  the  size  of  the  plate  and  punch  holes 
in  it  for  the  pins  to  protrude  through  (B).  Next  cut  a  piece  of  20  or 
22-carat  gold  plate  or  clasp  gold  to  the  same  size  and  also  punch  holes 
in  it  for  the  pins  in  the  same  manner  as  for  the  solder  (C).  Place  the 
solder  on  the  plate  and  the  supplementary  plate  over  the  solder,  and 
apply  the  broad  flame  of  the  blowpipe.  When  the  solder  melts,  the 
supplementary  piece  of  plate  will  settle  into  position.  If  one  piece  of 
plate  does  not  give  sufficient  length  to  the  tip,  attach  in  the  same  man- 
ner another  layer  of  gold  solder  and  plate.  When  extreme  hardness  is 
required,  use  clasp  gold  instead  of  plate.  If  three  pins  are  used,  it  is 
very  seldom  necessary  to  extend  the  plate  for  stability  beyond  the 
incisal  surface  over  the  lingual  side  of  the  tooth.  A  slight  depression 
in  the  incisal  surface  may  be  formed  if  it  does  not  already  exist  in  the 
central  part  between  the  pins,  as  shown  in  section  in  Fig.  466.  This 
depression  aids  in  steadying  the  finished  tip. 
1  Dr.  Milton  Smith's  method. 


PARTIAL  CROWN-WORK  235 

Fig.  467  shows  the  reproduction  of  the  occlusal  surface  of  a  molar 
by  the  methods  described,  in  which  three  pins  are  inserted.  Some  cases 
of  reproduction  of  the  occlusal  section  may  be  done  to  advantage  by  the 
casting  method.  In  such  cases  the  matrix  should  be  made  of  platinum, 
gage  MooOj  and  the  pins  are  best  soldered  with  15  per  cent,  platinum 
solder  instead  of  pure  gold. 

When  pins  are  used  to  retain  a  gold  tip  in  the  reproduction  of  an 
occlusal  surface,  the  matrix  method  is  generally  preferable. 

When  the  entire  "bite"  is  to  be  opened,  one  tooth  on  each  side 
should  be  first  elongated  and  used  to  gage  the  space  for  the  lengthening 
of  the  others. 


CHAPTER  XIX 

PARTIAL  CROWN-WORK,  CONTINUED 

INDIRECT  METHOD  OF  FORMATION  OF  INLAYS — COMPARATIVE  MERITS 
— IMPRESSION  MATERIALS — PROCESS — ^IMPRESSION  TUBES,  CAPS 
AND  TRAYS — FORMATION  OF  TUBES  AND  CAPS — METHOD  OF  FORM- 
ING TRAYS  AND  TAKING  IMPRESSIONS — INLAY  DIES — INDIRECT 
INLAY  WAX  MODEL  FORMATION — METALLIC  MATRICES,  INDIRECT 
METHOD 

Indirect  Method  of  Formation  of  Inlays. — The  construction  of 
inlays  by  the  indirect  method  differs  from  that  already  explained  in 
that  the  work  is  done  on  a  model  instead  of  directly  in  the  mouth. 

Comparative  Merits. — In  the  direct  method  the  labor  of  taking  an 
impression  and  making  a  die  and  models  is  avoided  and  accuracy  of  the 
occlusion  in  the  finished  inlay  is  assured. 

By  the  indirect  method  the  formation  of  the  wax  inlay  model  is 
comparatively  simplified,  especially  in  positions  difl&cult  to  reach  in  the 
mouth.  In  removal  of  the  wax  model,  distortion  of  the  body  or  edges 
is  less  liable  to  occur,  a  matter  difficult  or  impossible  to  correct  in  the 
cast  inlay.  Any  slight  discrepancies  in  the  cast  inlay  are  more  easily 
detected  and  corrected  by  the  metal  model  than  they  can  be  in  the 
mouth. 

As  articulating  models  can  seldom  be  depended  upon  as  absolutely 
correct,  inaccuracies  of  the  occlusal  surface  are  more  liable  to  occur  in 
their  use  than  when  made  directly  in  the  mouth.  Such  inaccuracies 
call  for  alterations  which  are  not  always  as  easily  made  with  gold  as 
with  porcelain  and  which  at  times  destroy  the  sulci  and  cusps  which 
have  involved  labor  and  skill  in  their  formation. 

Impression  Materials. — Inlay  impression  compound  that  softens 
at  a  low  temperature,  hardens  quickly  and  reproduces  the  smallest 
details  of  form,  is  used  for  taking  inlay  impressions  in  preference  to 
gutta-percha  or  any  of  the  other  materials  and  preparations  formerly 
used. 

Process. — The  impression  compound  is  softened  by  dry  heat  to  a 
doughy  consistence,  the  proper  quantity  is  then  placed  in  a  cap,  tube 
or  tray  with  a  cone-shaped  extension  to  press  into  the  cavity.  Just 
before  the  impression  is  taken  the  cone  and  the  surface  of  the  compound 

236 


PARTIAL  CROWN -WORK 


2.37 


are  additionally  softened  by  holding  above  a  flame  for  a  moment.. 
The  softened  part,  especially  the  cone,  is  then  more  easily  pressed  into 
the  cavity  and  the  harder  part  back  of  it  offering  greater  resistence 
forces  the  soft  portion  forward.  The  surplus  compound  that  is  forced 
out  of  the  rear  end  of  the  tube  or  cap  should  be  pressed  back  at  once, 
forming  a  piston  to  drive  the  soft  portion  into  the  cavity  and  onto  and 
over  its  edges. 

An  impression  should  be  allowed  to  remain  in  position  before  removal 
until  the  compound  is  hard.  The  hardening  may  be  hastened  by  the 
application  of  cold  water  or  a  draught  of  cool  air. 

Impression  Tubes,  Caps  and  Trays. — Various  forms  of  small  im- 
pression tubes,  caps  and  trays  are  given  preference  for  gold  and  por- 
celain inlay  impressions.  The  use  of  caps  and  tubes  is  confined  to  those 
cases  where  the  impression  is  inserted  and  removed  in  an  incisal  or 
occlusal  direction,   such   as  approximal-occlusal,  occlusal  and  incisal 


Pig.  468. 


cavities.  Trays  are  used  generally,  but  especially  for  cervico-Iabial 
and  buccal  cavities  and  such  approximal  and  other  positioned  cavities 
as  require  the  impression  to  be  removed  in  a  more  or  less  lateral  direc- 
tion. In  the  use  of  tubes  and  caps,  the  metal  partly  or  entirely  sur- 
rounds the  tooth,  and  with  trays,  only  fits  over  the  cavity  and  adjacent 
portion  of  the  crown.  In  the  use  of  either  form,  the  metal  when  trim- 
med should  always  be  allowed  to  entirely  cover  the  cavity  and  extend 
beyond  the  margin  at  least  one-eighth  of  an  inch  on  the  surface  of  the 
crown  and  one-sixteenth  of  an  inch  on  the  root  at  the  cervico-approxi- 
mal  section. 

Formation  of  Tubes  and  Caps. — These  are  generally  made  of  copper 
No.  32  or  thinner,  and  when  annealed  are  very  flexible.  (See  Part  I, 
Chapter  V.) 

The  tube  or  cap  used  should  be  one  selected  or  made  which  will 
closely  fit  over  and  encircle  the  tooth.  Fig.  468  represents,  in  section 
a  tube  fitted  to  a  molar.  The  dotted  line  indicates  the  position  a  cap 
would  take  if  used  instead  of  a  tube.  Fig.  469  illustrates  the  Roach  im- 
pression cup  or  tray  with  a  hole  for  a  detachable  handle.     The  cup 


238 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


should  be  bent  and  trimmed  to  the  form  of  the  tooth  and  requirements 
of  the  case,  the  same  as  a  tube  would  be. 


Pig.    469. 


Methods  of  Forming  Trays  and  Taking  Impressions. — Trays  are 
generally  made  to  meet  the  special  requirements  of  a  case.  German 
silver  plate  or  an  alloy  of  nickel  and  silver  termed  platinoid,  about  No, 


B 


Pig.  470. 

30  gage,  is  very  suitable.  The  plate  is  cut  and  bent  to  fit  the  approxi- 
mal  space  and  side  or  sides  of  the  crown,  or  to  cover  only  the  cavity  and 
a  portion  of  the  crown,  as  in  cervical  and  occlusal  cavities. 


PARTIAL  CKOWN-WOKK 


2.39 


A  simple  labial  cavity/  as  illustrated  at  A,  Fig.  470  will  be  used  as 
a  typical  case  to  explain  the  formation  and  use  of  a  tray.  A  strip  of 
platinoid  is  cut  to  the  shape  shown  at  B,  and  perforated  with  a  plate- 
punch  to  aid  in  retaining  the  impression  compound. 

A  small  piece  of  the  compound  is  softened  over  a  flame  formed  in 
a  cone  on  the  tray,  as  shown  at  C,  the  tray  being  first  heated  sufficiently 
to  secure  good  adhesion.  The  cone  is  then  partly  chilled  by  dipping  it 
in  cold  water,  after  which  the  point  of  the  cone  is  softened  by  holding 
for  a  moment  in  a  flame  and  then  quickly  carried  to,  and  pressed  into 
the  cavity  with  the  index  finger  resting  against  the  lingual  side  of  the 
tooth,  while  the  thumb  carries  the  compound  to  place,  as  shown  at  D, 
and  holds  it  rigid  in  position  during  the  cooling.  When  occasion  re- 
quires, the  position  of  the  fingers  may  be  reversed.  The  removed  im- 
pression is  shown  at  E. 


Fig.  471. 

The  hardening  of  the  compound  may  be  hastened  by  cold  water. 
If  the  cavity  has  been  properly  prepared,  the  tray  correctly  shaped 
and  the  compound  suitably  applied,  the  impression  is  usually  dislodged 
without  much  difficulty.  The  imprint  of  the  cavity  and  margins  should 
be  sharply  defined.  Rough  places  indicate  either  faulty  shaping  of  the 
cavity  or  imperfections  in  the  impression. 

In  cervical  cavities  extending  under  the  gingival  margin  it  is  ad- 
visable to  first  prepare  the  cavity  for  the  inlay,  pack  it  with  gutta- 
percha and  press  back  the  gum  for  a  day  or  two  before  taking  the  im- 
pression. In  such  cases  the  tray  should  be  shaped  and  curved  so  that, 
if  necessary,  one  edge  may  be  forced  up  under  the  gum  between  the 
soft  tissues  and  the  concealed  margin  of  the  cavity.  The  compound 
is  attached  to  the  tray,  leaving  the  extreme  edge  exposed,  or  nearly 
so,  and  the  edge  introduced  beyond  the  concealed  margin  of  the  cavity 
before  the  tray  is  pressed  down. 

In  cases  where  there  is  convexity  of  surface,  such  as  is  illustrated 
at  A,  Fig.  471,  the  metal  is  cut  and  bent  in  forming  the  tray  to  accurately 
fit  over  the  tooth  surface  as  shown  at  B  and  C. 

1  Dr.  F.  T.  Van  Woert's  method  of  formation  is  here  presented. 


240 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Fig.  472. 


Fig.  473- 


Fig.  474. 


PARTIAL  CROWN-WORK 


241 


When  a  cervical  cavity  extends  around  the  approximal  side,  as 
illustrated  at  A,  Fig.  472,  the  metal  should  be  cut  and  the  tray  shaped 
as  shown  at  B  and  C. 

In  cases  of  molars,  as  illustrated  at  A,  Fig.  473,  the  tray  is  formed 
and  impression  taken,  as  shown  at  B,  C,  D  and  E. 


Fig.  475- 


For  a  cavity  wholly  in  the  distal  surface  of  a  molar  with  space 
posterior  to  it,  as  shown  at  A,  Fig.  474,  the  tray  is  shaped  and  impres- 
sion taken,  as  shown  at  B,  C,  D  and  E. 

The  taking  of  approximal  cavity  impressions  in  trays  is  more  complex 


16 


242 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


than  those  just  explained.  Fig.  475  shows  a  cavity  in  the  labial  ap- 
proximal  surface  of  an  upper  central  incisor.  The  tray  is  shaped,  as 
shown  at  A.  Only  enough  metal  is  used  to  completely  cover  the  mar- 
gins of  the  cavity  and  thus  avoid  injury  to  the  tissue  by  overhanging 
edges  of  the  compound,  which  will  interfere  with  removal  of  the  im- 
pression. The  surface  of  the  compound  is  quickly  heated  and  placed 
in  the  cavity,  as  shown  at  B,  and  a  small  cement  spatula  is  forced  be- 
tween the  outer  surface  of  the  tray  and  the  adjoining  tooth. 


Fig.  476. 

After  cooling  and  before  removing  the  spatula,  any  excess  of  the 
compound  that  may  be  forced  through  upon  the  lingual  side,  as  shown 
at  C,  should  be  cut  away  with  a  lance.  The  spatula  is  first  removed 
and  then  the  impression.  A  spatula  forced  in  as  described,  on  being 
removed,  furnishes  a  slight  space  for  displacement  and  removal  of  the 
tray. 

In  the  lingual  approximal  surface  (Fig.  476)  a  similar  tray  (A)  is 
used  but  it  is  bent  end  curved  to  fit  the  lingual  surface.  When  the 
impression  is  taken,  it  is  pulled  to  place  (B)  and  a  bent  spatula  (C) 


PARTIAL  CROWN -WORK 


243 


is  inserted  from  the  lingual  side.     Its  further  treatment  is  identical 
with  the  previous  case. 

Approximal  cavities  involving  both  the  labial  and  lingual  surfaces, 
such  as  is  shown  in  Fig.  477,  present  complications  as  the  impression 
cannot  be  removed  in  one  piece  but  must  be  taken  in  a  tray  formed 


in  two  sections.  The  first  is  like  that  shown  at  A;  the  second  is  cut 
in  shape  as  depicted  at  B,  and  bent  as  at  C.  This  should  fit  the  first 
section  closely  without  lateral  motion,  yet  slide  up  and  down  freely  (D). 
The  impression  is  taken  by  introducing  the  compound  lingually  on 
the  firstjsection  (E).     The  spatula  should  be  held  in  place  by  an  assist- 


244 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


ant  at  the  angle  shown,  so  that  it  will  not  interfere  with  the  second  part 
of  the  tray,  when  it  is  subsequently  forced  to  place. 

The  surplus  compound  is  next  removed  and  that  remaining  carved 
to  the  contour  of  the  labial  surface  and  flush  with  the  cavity  margin, 
as  shown  at  F.  The  surface  of  the  tooth  and  the  carved  impression  are 
coated  with  vaselin.  The  second  section  (C)  is  prepared  by  attach- 
ing to  its  surface  a  small  quantity  of  impression  compound  but  not 


Fig.  478. 

enough  to  press  beyond  the  margins  of  its  attachment.  The  compound 
is  heated  and  this  second  section  is  slipped  over  the  first  section  (F) 
and  pressed  to  place  as  shown  at  G.  When  chilled  the  second  section 
is  first  removed,  the  spatula  next  and  then  the  first  section.  After 
removal  the  parts  are  adjusted  together  and  fastened  with  adhesive 
wax.  If  properly  performed  the  result  will  not  exhibit  a  perceptible 
seam.     This  sectional  method  is  applicable  to  a  variety  of  cases. 


Fig.  479- 

Fig.  478  shows  the  form  of  a  tray  and  method  of  shaping  suitable 
for  an  occlusal  cavity  extending  into  the  buccal  region. 

Fig.  479  shows  a  distal  cavity  in  a  molar  and  the  formation  of  a  tray 
suitable  for  it.  For  cavities  in  the  mesial  approximal  surface,  the  tray 
described  for  the  distal  approximal  surface  is  to  be  bent  over  on  itself 
as  seen  in  Fig.  480. 

When  a  cavity  includes  the  occlusal,  buccal  and  both  approximal 
surfaces,  a  tray  slightly  more  intricate,  such  as  is  shown  in  Fig.  481  is 


PARTIAL  CROWN-WORK 


245 


req\iired.  The  main  part  of  the  tray  is  first  bent  to  fit  the  distal  and 
lingual  sides  as  has  been  shown  in  Fig.  479.  Next  a  piece  of  plate  is 
cut  and  bent  as  shown  at  A  and  B,  Fig.  481,  and  soldered  to  the  first 
or  main  part  as  illustrated  at  C. 

Fig.  482  shows  a  tray  for  a  bicuspid  where  the  cavity  involves  the 
mesial,  occlusal  and  distal  surfaces.     The  metal  is  cut  and  bent,  as 


Pig.  480. 

seen  at  A,  B  and  C,  to  form  the  tray,  which  is  applied  from  the  buccal 
side. 

Fig.  483  shows  an  upper  central  prepared  for  a  porcelain  or  gold 
contour  corner  restoration.  A,  B  and  C  show  the  formation  of  the 
tray  and  D  the  tray  and  impression. 

When  the  cavity  is  deep-seated,  as  shown  by  dotted  line  in  Fig. 
484,  the  cavity  is  first  filled  with  a  cone  of  the  impression  compound  A, 
and  pressed  in  as  seen  at  B.     The  surface  of  the  cone  is  then  heated 


Fig.  481. 

with  a  hot  spatula  and  the  impression  is  taken  as  in  the  previous  case. 
When  the  impression  is  removed,  it  appears  as  though  in  one  piece  (C). 
Before  inserting  the  cone  plug,  slightly  vaselin  the  cavity  to  aid  removal. 
In  cases  of  extensive  restoration  of  the  incisal  end  of  a  pulpless 
tooth,  represented  in  Fig.  485,  an  iridio-platinum  post  is  fitted  to  the 
proper  depth  in  the  canal  and  the  protruding  end  flattened.  The  post 
is  heated,  surrounded  with  a  cone  of  the  impression  compound  A,  and 
pressed  to  place  as  in  the  previous  case.     The  remainder  of  the  impres- 


246 


CROWN-,  BRIDGE-,  AND  PORCELAIN  WORK 


B 


^^ 


V_ 


Fig.  482, 


/ 


Fig.  483. 


PARTIAL  CROWN-WORK 


247 


sion  is  taken  in  a  loose-fitting  tube  or  cap,  B  and  C.  Before  pressing 
the  tube  or  cap  to  place  with  the  impression  compound,  the  end  of  the 
post  and  also  at  the  same  time  the  exposed  surface  of  the  compound 
should  be  heated  with  a  very  hot  spatula. 


B 


Pig.  484. 

In  cases  of  similar  restoration  for  a  vital  tooth  two  or  three  pins  of 
platinum  wire,  about  No.  20  or  21  gage,  should  be  fitted  closely  but 
easily  in  holes  drilled  parallel  on  each  side  of  the  pulp,  at  right  angles 
to  the  incisal  edge,  as  shown  in  Fig.  486.     The  impression  is  taken  in  a 


Fig.  485. 

manner  similar  to  the  case  in  Fig.  485,  the  pins  being  drawn  in  the 
compound. 

Inlay  Dies. — Various  materials  have  been  recommended  for  the 
formation  of  dies  for  inlay  work.  Practical  experience  suggests  amal- 
gam as  the  most  suitable.     A  silver-tin^  or  copper  amalgam  is  most  used. 

1  S.  S.  White  True  Dentalloy  is  of  this  form. 


248  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

The  silver-tin  amalgam  is  preferred  to  the  copper,  as  it  hardens  quickly. 
The  copper  amalgam  is  less  expensive  as  it  can  be  used  several  times. 
(See  Part  I,  Chapter  V.) 

The  die  should  be  inserted  in  a  wax  or  compound  impression  of  the 
tooth  and  the  adjoining  teeth,  with  "bite"  and  plaster  models  made 
from  which  the  die  may  be  removed  and  replaced.  The  shank  of  the 
die  should  be  tapered  and  veneered  with  wax  to  permit  easy  withdrawal 
from  the  plaster  model. 

Indirect  Inlay  Wax  Model  Formation. — The  process  of  wax  model 
formation  from  a  model  is  the  same  in  principle  as  the  process  in  the 
mouth.  The  die  may  be  removed  from  the  model  to  facilitate  the 
work  and  replaced  again  in  the  model  to  accurately  determine  the 


Pig.  486. 

contour,  also  the  form  of  the  occlusal  surface,  by  closing  the  articulat- 
ing model  on  the  wax.  Should  the  wax  become  chilled  during  the 
operation,  the  model  and  wax  in  position  may  be  immersed  for  a  while 
in  tepid  water  of  about  110°  F.  The  sprue  wire  is  best  inserted  in  the 
wax  model  while  it  is  still  in  the  die.  The  whole  is  then  chilled  and  the 
wax  model  removed. 

Metallic  Matrices,  Indirect  Method.^MetalHc  matrices  are  shaped 
on  an  amalgam  model  as  in  the  mouth.  Any  post  or  pins  present  in 
the  model  are  to  be  attached  in  position  with  wax  to  the  matrix,  invested 
and  soldered  to  it.  The  wax  model  is  then  formed  and  cast  in  the 
matrix.  For  further  descriptive  details  and  use  of  a  swager  to  shape 
a  matrix,  see  Part  VT,  Chapter  VI. 


CHAPTER  XX 
SPECIAL  OPERATIONS  IN  CROWN-WORK 

CROWNING  MOLAR  ROOTS  DECAYED  APART  AT  THE  BIFURCATION — CANII- 
LEVER  CROWN — METHOD  OF  CONSTRUCTION — METHODS  OF  CROWN- 
ING IN  CASES   OF  IRREGULARITY 

Crowning  Molar  Roots  Decayed  Apart  at  the  Bifurcation.— The 

roots  of  a  molar  decayed  apart  at  the  bifurcation  can  often  be  crowned 
serviceably.  The  roots  having  been  treated  the  ends  are  trimmed  and 
paralleled,  the  one  to  the  other,  giving  the  sides  a  slightly  tapering 
form.  Platinum  collars  No.  38  gage  are  made  and  fitted  to  each  root, 
reinforced  with  pure  gold,  floors  added  and  the  two  caps  soldered 
together  (Fig.  487).  An  occlusal  cast  section  can  then  be  added.  The 
most  serviceable  method  of  restoration  in  such  cases  is  accomplished 
with  platinum  and  porcelain.     (See  Part  VI,  Chapter  VIII.) 


Pig.  487. 


Pig. 


Pig.  489. 


In  cases  of  pyorrhea  alveolaris,  when  the  buccal  roots  of  a  first 
superior  molar  are  only  slightly  affected  but  the  connective  tissue  of 
the  palatal  root  is  nearly  or  entirely  destroyed, — a  condition  impossible 
to  treat  successfully, — ^the  usefulness  of  the  tooth  may  be  retained  in 
part  by  the  removal  of  the  palatal  section  of  the  crown  and  with  it  the 
root. 

The  buccal  roots  having  been  treated  and  filled,  a  fissure  bur  is 
inserted  in  the  pulp-chamber,  and  the  crown  cut  in  half  mesially  and 
distally  through  its  center.  The  palatal  half  of  the  crown  and  the 
palatal  root  are  then  removed.  The  buccal  half  of  the  pulp-chamber 
is  shaped  (Fig.  488)  to  retain  either  a  gold  inlay  or  an  amalgam  filHng, 
or  preferably  a  porcelain  inlay  such  as  will  give  form  to  the  part  as 
illustrated  by  Fig.  489.  In  case  of  extensive  decay  being  present,  cap- 
ping with  metal  may  be  resorted  to. 

249 


250 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Cantilever  Crown. — A  cantilever  crown  is  one  with  a  lug  on  the 
side  which  rests  on  but  is  not  connected  to  an  adjoining  tooth  or  crown, 
for  the  purpose  of  bridging  a  small  space.  Fig.  490  shows  the  applica- 
tion of  a  cantilever  crown  set  upon  a  second  bicuspid  with  a  lug  that 
bridges  the  space  formed  by  the  loss  of  the  first  bicuspid  and  resting 
on  the  cuspid  so  as  to  connect  the  broken  line  of  masticating  surface 
and  prevent  tilting  forward  of  the  second  bicuspid.  Fig,  491  illustrates 
the  application  of  two  cap-crowns  which  are  constructed  so  as  to  form 


Pig.  490. 


Fig.  491. 


Fig.  492. 


a  cantilever  bridge  over  a  small  space,  in  such  a  manner  as  to  prevent 
tilting  or  sliding  of  surfaces  and  at  the  same  time  be  easily  cleaned  with 
floss  silk.  A  single  root  of  a  lower  molar  may  be  capped  with  a  lug 
extending  to  and  resting  on  an  adjoining  tooth  in  the  manner  described 
in  either  of  these  cases. 

Method  of  Construction. — A  lug  such  as  has  just  been  described  to 
span  a  wide  interdental  space  is  conveniently  formed  by  first  attach- 
ing the  edge  of  a  piece  of  platinum  plate  about  gage  No.  30  to  the  side 


Fig.  493. 


of  the  gold  crown  with  wax  or  solder.  The  crown  is  then  fitted  in  the 
mouth,  the  platinum  bent  and  burnished  over  on  the  adjoining  tooth 
or  crown,  as  shown  in  Fig.  492,  and  removed.  The  space  A  is  filled  with 
wax  and  the  crown  invested.  The  wax  is  removed  with  boiling  water, 
the  aperture  A,filled  with  gold  foil  or  Corona  gold  to  prevent  contrac- 
tion of  the  platinum  by  the  solder,  heated  and  soldered.  The  surplus 
metal  is  trimmed  away,  as  indicated  on  adjustment  in  the  mouth. 


SPECIAL  OPERATIONS  IN  CROWN-WORK 


251 


Method  of  Crowning  in  Cases  of  Irregularity. — Fig.  493  represents 
a  case  of  irregularity  as  treated  by  Dr.  Bonwill.  On  account  of  the 
poor  character  of  the  teeth,  their  position  in  the  palatal  arch  and  the 
age  of  the  patient,  it  was  considered  beyond  correction. 

Fig.  494  shows  a  method  of  treating  a  case  of  irregularity  without 
destroying  the  vitality  of  the  pulp.^     The  tooth  at  B  which  stood  inside 


Fig.  494. 


the  line  of  the  lower  teeth  when  the  mouth  was  closed,  was  trimmed, 
shaped  and  capped  without  removing  the  pulp.  To  this  cap  was 
attached  the  tooth  A,  with  an  oval-shaped  piece  of  gold  for  cleanliness 
that  cleared  the  lower  teeth  in  occlusion.  The  cap,  which  was  then 
cemented  over  the  natural  crown,  was  entirely  hidden  from  view  by 
the  artificial  tooth  or  porcelain  facing. 
1  Case  of  the  author's. 


CHAPTER  XXI 
TREATMENT  BY  CROWN-WORK  OF  FRACTURED  TEETH  AND  ROOTS 

FRACTURED  CROWNS  AND  ROOTS — LONGITUDINAL  FRACTURES — SLANT- 
ING FRACTURES — ^INLAY  CASTING  METHOD — USE  OF  A  CAST  OF  A 
FRACTURED  PORTION — AMALGAM — POST  AND  AMALGAM 

Fractxired  Crowns  and  Roots. — The  fracture  of  teeth  or  roots  is 
caused  either  by  a  blow,  or  strain  of  mastication.  Fractures  are  longi- 
tudinal or  slanting.  The  longitudinal  fracture  passes  lengthwise 
through  the  crown,  dividing  the  tooth  into  two  parts  (Fig.  495).  The 
slanting  extends  from  the  center  or  between  the  cusps  to  the  side  on  the 
line  of  the  cervix  or  beyond  it. 

The  crowning  of  fractured  teeth  or  roots  is  an  operation  that  re- 
quires skill  and  delicate  treatment.  Its  practicability  depends  on 
the  nature  of  the  fracture,  the  present  health  of  the  parts  and  the  length 
of  time  that  has  elapsed  since  the  occurrence  of  the  injury. 

Longitudinal  Fractures. — Foreign  substances  having 
been  removed  from  within  and  around  the  parts,  the 
crevice  of  the  fracture  is  syringed  thoroughly  with  tepid 
saline  solution  and  then  with  alcohol.  The  fractured 
parts  of  the  root  are  drawn  together  and  ligated  with 
a  piece  of  orthodontia  wire  fastened  by  twisting  the  ends. 
If  considerable  inflammation  is  present,  allow  the  tooth  to  rest 
until  the  inflammation  subsides.  If  there  is  no  inflammation,  or  only 
a  slight  amount,  immediately  shape  up  the  coronal  section  for  the  col- 
lar. Trim  the  sides  to  the  inner  line  of  the  wire  ligature,  fit  a  copper 
tube,  take  an  impression  of  the  tooth  in  impression  compound  and  make 
an  amalgam  die.  If  the  condition  of  the  fracture  will  permit,  the  liga- 
ture should  be  removed  when  the  impression  is  taken,  but,  if  not,  allow 
it  to  remain  and  trim,  also  deepen  the  cervical  shank  of  the  die  enough 
to  remove  the  form  of  the  wire.  The  root-canals  should  be  opened, 
dried  and  heated  with  a  current  of  hot  air  from  a  hot-air  syringe  and 
packed  with  a  saturated  solution  of  aristol  and  oil  of  cloves  and  sealed 
with  gutta-percha.  This  treatment,  with  renewal  of  dressings,  is  to 
be  continued  until  a  sterilized  condition  is  estab  lished. 

The  root-canals  only  are  to  be  first  filled  and  not  the  trunk  of  the 
pulp  cavity  where  the  fracture  is.     Use  oxyphosphate  instead  of  oxy- 

252 


CROWN-WORK  OF  FRACTURED  TEETH  AND  ROOTS  253 

chlorid  of  zinc  in  the  filling  of  the  canals  if  there  is  any  danger  of  the 
oxychlorid  invading  the  crevice  of  the  fracture  and  causing  inflamma- 
tion, which  is  usually  the  case. 

When  the  collar  has  been  made,  the  ligature  is  removed,  the  collar 
fitted  and  the  remainder  of  the  artificial  crown  completed.  When  the 
crown  is  ready  to  insert,  the  fractured  parts  are  again  syringed  with 
saline  solution,  then  alcohol,  and  the  cavity  filled  with  cotton  saturated 
with  alcohol. 

The  tooth  is  protected  from  the  secretions,  the  cotton  removed  and 
the  cavity  dried  with  hot  air.  A  quantity  of  copper  oxyphosphate  is 
mixed  to  the  consistence  of  a  thin  cream,  the  fractured  parts 
are  slightly  separated  and  the  cement  gently  pumped  into 
the  crevice  of  the  fracture  and  the  cavity  in  the  crown 
filled.  A  ligature  is  then  instantly  applied  and  made  as 
tight  as  possible.  As  the  parts  are  brought  together,  the 
surplus  cement  in  the  fracture  is  forced  back  into  the 
cavity  of  the  tooth.  Any  pressure  the  cement  may  exert 
against  the  pericementum  is  so  slight  that  no  serious  or 
permanent  inflammation  is  likely  to  follow.  The  tooth  should  not  be 
disturbed  until  the  cement  has  thoroughly  set.  The  ligature  is  then 
removed  and  the  finished  cap-crown  cemented  in  position.  The  intro- 
duction of  the  cement  in  the  fracture,  as  described,  shows  better  re- 
sults than  when  confined  only  to  the  cavity  of  the  tooth,  as  by  its 
presence  the  secretions  are  more  effectually  excluded. 

The  cervical  edge  of  the  collar  should  be  brought  to  a  feather  edge 
and  thoroughly  burnished  to  the  sides  of  the  root.  The  crown  should 
be  favored  by  leaving  a  very  slight  space  between  it  and  the  occluding 
teeth.  This  space  will  gradually  close  in  time  and  the  tooth 
may  be  better  able  to  withstand  the  force  of  occlusion. 

Another  method  in  the  case  of  molars  with  comparatively 
Pj^7497.  straight  root-canals  is:  With  the  ligature  in  position  drill  the 
root-canals  as  deep  as  possible  parallel  to  each  other;  fit  a 
post  with  a  long  end  in  each  canal,  wax  and  remove  the  posts  together 
in  position,  invest  and  connect  with  a  piece  of  plate,  trim  off  the 
surplus  ends,  as  shown  in  section  in  Fig.  496  and  cement  the  posts 
in  the  roots.     Cap  with  a  closely  fitted  collar  crown. 

Another  method,  if  the  dentin  is  strong  enough  to  favor  it,  is  to 
ligature  the  roots,  drill  two  dovetail  slots — one  in  each  fractured  sec- 
tion— and  having  filled  the  root-canals  and  the  inner  section  of  the 
pulp-chamber  with  cement,  fill  the  slots  with  a  hard,  quick-setting 
amalgam  (Fig.  497).  In  shaping  the  crown  and  roots  for  the  gold 
collar,  care  should  be  taken  not  to  loosen  the  amalgam  splint. 


254 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


A  great  drawback  in  these  cases  is  that  the  patient  generally  fails 
to  present  himself  immediately  for  treatment,  and  foreign  substances 
invade  the  fracture,  causing  infection  and  inflammation  which  is 
impossible  to  control.  Even  in  the  apparently  most  favorable  case, 
subsequent  to  treatment  a  septic  condition  of  the  fracture  usually  super- 
venes in  time,  the  irritation  caused  thereby  and  the  exudations  from  the 
fracture  compelling  the  patient  to  resort  to  extraction. 

Slanting  Fractures.^ — Fractures  of  this  form  occur  in  bicuspids  and 
molars  where  large  fillings  are  inserted  from  the  mesial  to  the  distal 
side,  leaving  the  separated  buccal  and  lingual  cusps  to  bear  the  brunt 
of  mastication.  The  fracture  seldom  extends  beyond  the  edge  of  the 
alveolar  process.  Fractures  of  this  kind  usually  occur  with  pulpless 
teeth. 

The  fractured  part  is  removed.  The  hemorrhage  is  checked  and  the 
part  anesthetized  with  cocain  and  adrenalin.     If  the  fracture  extends 


.:j 


Fig.  498. 


Pig.  499. 


Fig.  500.     Fig.  501.        Fig.  502. 


below  the  edge  of  the  alveolus,  the  bone  is  removed  to  the  line  of  the 
fracture. 

The  canals  are  prepared  for  treatment  and  gutta-percha  packed 
into  the  cavity  of  the  tooth  and  the  tissue  pressed  back  to  expose  the 
surface  and  margins  of  the  fracture. 

Inlay  Casting  Method.- — ^In  the  case  of  a  bicuspid  fractured  as  shown 
in  Fig.  498,  a  large  platinum  or  iridio-platinum  post  is  fitted  into  the 
canal.  The  post  is  heated  and  veneered  with  adhesive  wax.  A  pellet 
of  inlay  wax  is  softened  and  pierced  with  the  post.  The  post  is  ad- 
justed to  position  in  the  canal,  the  wax  adapted  and  shaped  to  the 
form  of  the  lost  fractured  part  and  all  removed.  A  sprue  wire  is  in- 
serted in  the  wax  form  as  shown  in  Fig.  499,  and  invested  and  cast 
with  pure  gold.  The  casting  is  then  polished,  the  excess  of  post  cut 
off  and  the  inlay  cemented  to  position  with  oxyphosphate.  In  such  a 
case  the  cusps  should  be  shortened  by  grinding  to  lessen  stress  in 
occlusion. 


CROWN-WORK  OF  FRACTURED  TEETH  AND  ROOTS  255 

Use  of  Cast  of  Fractured  Portion. — Another  method,  where  the 
fracture  is  of  the  form  shown  in  Fig.  498,  is  to  cast  the  removed  frac- 
tured portion,  then  place  and  retain  the  cast  replica  in  position  by 
soldering  it  to  a  root  post.  The  gold  repHca  of  the  fractured  part  is 
made  by  pressing  the  fractured  side  into  the  surface  of  impression 
compound;  chilling,  removing,  trimming  compound  close  to  the  edge 
of  the  impression,  and  forming  the  wax  model,  then  casting. 

Fig.  500  illustrates  a  prepared  fractured  root  with  a  casting  for  a 
porcelain-faced  jacket-crown,  and  Fig.  501  for  a  gold  cap-crown. 

Amalgam. — The  preceding  methods  present  an  artificial  restoration 
having  a  metallic  surface  only  slightly  oxidizable,  which  is  not  the  case 
when  amalgam  is  used  and  the  surface  is  left  exposed,  even  though 
polished.  The  use  of  amalgam  is  preferably  confined  to  fractures 
which  will  be  entirely  covered  with  the  collar;  or  to  those  that  extend 
so  far  under  the  gum  margin  that  a  gold  inlay  cannot  well  be  applied. 

Post  and  Amalgam. — A  post  in  a  root-canal  reinforced  with 
amalgam  affords  great  security.  Such  an  application  in  the  restoration 
of  a  bicuspid  for  a  porcelain-face  jacket-crown  is  illustrated  in  Fig. 
502.  The  post  should  be  made  of  gold  or  platinum,  with  a  globule  of 
gold  ^solder  melted  on  the  part  that  will  rest  in  contact  with  the 
amalgam.  The  use  of  posts  or  screws  made  of  alloys  of  the  base  metals 
is  not  permissible  in  these  operations. 

When  amalgam  is  used  to  restore  a  fractured  root,  the  collar  of  the 
crown  is  supposed  to  cover  it  except  in  cases  where  the  restoration  is 
very  deep  and  of  a  shape  that  is  preferably  left  uncovered. 


CHAPTER  XXII 
PROCESSES  CONNECTED  WITH  CROWN-  AND  BRIDGE-WORK 

CORRECTION  OF  EXCESS  OF  SOLDER — TO  SECURELY  ATTACH  A  CROWN 
— IMPORTANCE  OF  REMOVAL  OF  FLUX  FROM  INTERIOR  OF  CROWNS 
—CORRECTION  OF  INTERFERING  POINTS  IN  ADJUSTMENT  AND 
OCCLUSION 

Correction  of  Excess  of  Solder. — To  correct  the  accidental  presence 
of  solder  on  the  inside  of  a  gold  crown,  dry  the  surface  of  the  metal  and 
tooth  with  a  wisp  of  cotton  on  the  point  of  an  instrument,  and  with 
the  cotton  paint  the  surface  of  the  natural  tooth  or  root,  with  a  spat- 
ulated  paste  of  rouge  and  oil  and  then  adjust  the  crown.  The  inter- 
fering spot  will  be  accurately  marked  on  the  gold.  This  should  be 
trimmed  with  a  small  carborundum  point  and  the  crown  again  inserted 
to  determine  whether  enough  has  been  removed.  If  preferred,  the 
paste  may  be  placed  on  the  inside  of  the  gold  crown.     In  that  Vvay  the 


Fig.  503.  Fig.  504. 

interfering  point  will  be  marked  on  the  natural  tooth  or  root,  which 
can  be  trimmed  instead  of  the  gold  to  permit  proper  adjustment. 
The  latter  method  is  more  suitably  appHed  to  pulpless  teeth. 

To  Securely  Attach  a  Crown. — Cases  present  where  the  tooth  is 
short  and  the  occlusion  of  a  character  requiring  the  reduction  of  the 
collar  to  such  a  degree  as  to  suggest  insecurity  when  the  crown  is  ce- 
mented. In  such  a  case  with  a  living  pulp,  a  short  barbed  or  headed 
pin  that  will  anchor  in  the  natural  crown  should  be  soldered  in  the 
center  of  the  gold  crown,  as  shown  in  Fig.  503.  This  is  done  by  passing 
the  pin  from  the  cavo-surface  through  a  hole  drilled  in  the  occluding 
surface  of  the  crown  and  cementing  with  wax.  It  is  then  adjusted 
in  the  mouth,  removed,  invested  and  the  pin  soldered  from  the 
outside.  In  a  pulpless  tooth  the  pin  may  be  extended  into  the  pulp- 
chamber  or  a  root-canal  (Fig.  504). 

256 


CROWN-  AND  BRIDGE-WORK  257 

Importance  of  Removal  of  Flux  from  Interior  of  Crowns.^Always 

boil  a  crown  in  acid  to  remove  the  flux.  The  removal  of  the  flux  from 
the  cavo-surface  of  the  crown  is  absolutely  necessary  if  it  is  intended 
to  be  used  in  bridge-work,  as  solder  will  have  to  be  melted  on  the  outer 
surface  of  the  crown. 

Correction  of  Interfering  Points  in  Adjustment  and  Occlusion. 
In  adjustment,  especially  of  bridge- work,  interfering  points  are  indi- 
cated by  veneering  the  cavo-surface  of  the  cap  or  crown  with  a  paste 
of  rouge  and  oil.  On  adjusting  the  work  the  interfering  point  will  be 
marked  on  the  root  or  tooth,  which  should  be  trimmed  accordingly. 
The  method  can  be  reversed  by  applying  the  rouge  on  the  root  or 
tooth. 

In  occlusion  use  marking  paper  or  apply  the  rouge  and  oil  on  a 
strip  of  paper  and  occlude  the  teeth  on  the  paper.  Another  method  is : 
Warm  the  occlusal  surface  of  the  crown  and  veneer  it  with  a  film  of  wax 
then  occlude  the  teeth  on  the  wax.  (See  Part  IV,  Chapter  I,  Adjust- 
ment and  Insertion.) 


17 


CHAPTER  XXIII 

CEMENTATION  OF  CROWN-  AND  BRIDGE-WORK 

ZINC  OXYPHOSPHATE — METHOD  OP  MIXING — APPLICATION — GUTTA- 
PERCHA  METHOD  OP  CEMENTING  WITH  GUTTA-PERCHA  OR  GUTTA- 
PERCHA    CEMENT — METHOD     OF     MEASURING     GUTTA-PERCHA — ^TO 

APPLY  GUTTA-PERCHA  IN  THE  FORM  OF  A  FILM  OVER  A  SURFACE 

TO  CEMENT  THE  CROWN  OR  BRIDGE — FOR  TEMPORARY  INSERTION — ■ 
REQUIREMENTS  FOR  SUCCESS — OXYPHOSPHATE  IN  COMBINATION 
WITH  GUTTA-PERCHA  OR  GUTTA-PERCHA  CEMENT — SILICATE 
CEMENT — AMALGAM 

Zinc  Oxyphosphate 

As  a  cement  for  effecting  the  proper  union  between  the  natural 
tooth  or  root  and  the  artificial  crown,  zinc  oxyphosphate  is  generally 
preferred  and  in  many  respects  is  the  most  suitable  cement  that  has 
yet  been  found.  If  exposed,  even  the  best  preparations  are  slowly 
soluble  in  the  mouth  and  the  compound  permits  it  to  absorb  gases  and 
fluids  and  gradually  become  septic.  At  the  present  time  to  impart  anti- 
septic properties  to  zinc  oxyphosphate,  compounds  of  copper  are  in- 
corporated by  several  manufacturers  in  a  proportion  of  at  least  25  per 
cent.  A  silver  chlorid  cement  has  been  introduced  by  The  S.  S.  White 
Dental  Manufacturing  Co.,  for  which  antiseptic  properties  are 
claimed. 

Exact  scientific  proportions  of  the  chemical  substances  of  which  a 
cement  is  composed  are  essential  in  its  preparation.  The  zinc  oxid 
should  be  calcined  at  a  high  heat  and  then  ground  to  an  impalpable 
powder.  Cement  should  possess  the  property  of  being  uniformly  dense 
and  hard  clear  through  the  center  when  set,  after  being  mixed  thin  and 
formed  in  a  mass.  The  density  of  one  preparation  of  zinc  phosphate 
in  comparison  with  another  can  be  tested  by  placing  samples  of  each 
of  the  same  size,  mixed  under  similar  conditions,  in  red  ink.  After 
immersion  for  one  or  more  weeks,  the  samples  can  be  removed,  washed, 
then  cut  through  the  center  and  their  comparative  density  determined 
approximately  by  the  depth  of  the  stain. 

The  setting  of  the  best  preparations  of  pure  zinc  oxyphosphate  is 
materially  affected  by  temperature.  Thus,  a  cement  which  is  slow- 
setting  at  50°  F.  is  liable  to  be  quite  quick-setting  at  80°  F.     In  some 

258 


CEMENTATION  OF  CROWN-  AND  BRIDCE-WORK 


259 


of  the  preparations  of  cement,  an  effort  is  made  to  remedy  this  variation 
by  adulterating  with  various  ingredients,  but  this  tends  to  increase  the 
solubility  of  the  compound.  A  standard  preparation  of  cement 
answering  the  requirements  previously  outlined  should  be  used  in 
crown-  and  bridge-work. 

Method  of  Mixing. — For  all  styles  of  crowns  with  collars  and  for 
bridge-work  depending  on  crowns  of  similar  construction,  the  cement 
should  be  mixed  to  the  consistence  of  a  thick  cream,  but  for  crowns 
without  a  collar  or  ferrule,  it  may  be  moderately  thicker.  For  mixing 
the  cement,  a  piece  of  plate-glass  about  five  inches  long  and  three  inches 
wide  as  a  slab,  and  a  small  spatula,  are  suitable.  The  surface  of  the 
slab  should  be  perfectly  clean,  and  the  acid  and  powder  separately 


//i  dcCiud  di^i 


Fig.   505. — One-half  actual  size. 

placed  on  the  glass — the  powder  to  the  right  and  the  liquid  to  the  left — 
(Fig.  505),  the  quantity  of  the  powder  being  fully  equal  to  the  require- 
ments of  the  acid.  A  portion  of  the  powder  should  be  drawn  over  and 
mixed  with  the  acid  and  then  more  of  the  powder  added,  a  little  at  a 
time,  until  a  suitable  consistence — which  is  that  of  a  thick  cream — 
is  reached,  when  the  surplus  powder  should  be  instantly  pushed  aside 
and  the  mixing,  which  must  be  rapid  and  thorough,  continued.  It  is 
not  a  good  plan  to  mix  cement  excessively  thin  and  then  wait  until  it 
becomes  thickened  by  the  process  of  setting  to  a  consistence  suitable 
for  use.  The  resulting  compound  is  unnecessarily  acid,  the  overplus 
of  acidity  being  proportioned  to  the  excess  of  acid  used  over  the  quan- 
tity required,  and  its  character  as  a  cement  impaired.  On  the  other 
hand,  if  mixed  too  thick,  force  is  required  to  bring  the  crown  or  cap  to 
position^  and  the  thin  edges  of  collars  are  liable  to  be  sprung  from  the 


26o 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


sides  of  the  roots;  neither  will  the  cement  adhere  with  such  tenacity  to 
the  parts  as  when  mixed  to  a  proper  consistence.  If  the  slab  is  placed 
on  a  towel  that  has  been  saturated  with  ice  water,  the  cold  will  re- 
tard the  setting,  which  is  quite  advantageous  in  many  cases,  especially 
in  the  use  of  quick-setting  preparations  of  oxyphosphate.  In  this 
respect  the  sides  of  a  square  glass  bottle  filled  with  tap,  or  ice  water, 
and  well  corked  has  its  advantages  as  a  mixing  slab  in  hot  weather. 
Fig.  506  is  a  bottle  with  a  thermometer  inserted  to  indicate  the 
temperature.^ 

In  cementing  a  collar  crown  it  is  always  preferable  to  have  the 
cement  mixed  a  trifle  too  thin  rather  than  too  thick.  This  should  be 
borne  in  mind,  as  the  adjustment  of  many  a  well-fitted  crown  is  im- 
paired by  having  the  cement  mixed  too  thick. 

Application. — If  the  gum-margin  has  been  slightly  lacerated  and  is 
inclined  to  bleed,  adrenalin  or  adrenalin  and  cocain  should  be  applied 


Fig.  506. 

for  a  few  minutes.  The  parts  to  be  crowned  are  then  syringed  with 
tepid  water,  protected  by  a  napkin,  bathed  with  alcohol  applied  on 
cotton  with  tweezers  and  dried  with  absorbent  cotton  or  bibulous  paper. 
In  cases  where  the  prepared  teeth  or  roots  have  been  exposed  to  the 
action  of  the  secretions  of  the  mouth  for  one  or  more  days  during  the 
construction  of  the  work,  before  its  final  insertion  the  surface  of  the 
tooth  structure  also  should  be  thoroughly  cleaned  and  sterilized.  This 
is  effectively  done  with  fine  pumice  moistened  with  compound  tincture 
of  iodin  diluted  with  peroxid  of  hydrogen,  appHed  with  a  stick  or  brush 
point  over  the  entire  surface  of  the  tooth-structure  and  under  the  gum- 
margin.  The  iodin  not  only  aids  in  cleansing  and  sterilizing  the  parts 
but  also  acts  on  the  membrane  of  the  gingiva  as  an  astringent. 

A  rope  of  tightly  twisted  absorbent  cotton  may  be  wound  around 
each  crown  to  be  capped  and  pressed  close  against  the  gum,  with 
the  ends  twisted  together  at  the  labial  side  so  that  the  cotton  may 
be  easily  seized  and  instantly  removed  at  the  moment  the  cement  is 

'  Introduced  by  Dr.  W.  V.  B.  Ames. 


CEMENTATION  OF  CROWN-  AND  BRIDGE-WORK  261 

ready.  The  cotton  can  be  retained  in  position  over  and  around  a 
root  end  by  inserting  a  portion  in  the  orifice  of  the  canal.  Crown 
posts  may  be  slightly  barbed  or  roughened.  Collar  crowns  should  have 
been  previously  inserted  and  given  a  final  burnishing.  Each  cap  or 
crown,  having  been  thoroughly  cleaned  and  dried,  is  filled  with  enough 
cement  to  insure  a  slight  surplus.  A  small  portion  is  then  put  in  each 
root-canal  or  hollow  part  of  a  natural  crown  present,  and  the  artificial 
crown  or  bridge  immediately  adjusted  in  position. 

In  most  cases  it  is  best  to  remove  the  napkin  or  absorbent  cotton 
quickly  and  close  the  mouth  to  insure  the  occlusion  of  the  teeth,  and 
then  open  the  mouth  and  replace  the  napkin.  The  crown,  or  bridge, 
should  be  held  under  pressure  until  the  cement  has  set.  For  this  pur- 
pose a  piece  of  wood  notched  on  the  end  may  be  used.  In  setting  bi- 
cuspid or  molar  crowns  and  in  bridge-work,  it  is  better  in  the  majority 
of  cases  to  occlude  the  teeth  and  keep  them  in  position  under  a  steady 
pressure  until  the  cement  sets.  Under  these  circumstances,  the  saliva 
can  reach  only  the  surplus  portion  of  the  cement  and  cannot  interfere 
with  that  under  the  cap  or  crown.  One  thickness  of  thin  tin  foil  placed 
over  the  crown  as  the  teeth  are  occluded  will  slightly  increase  the 
pressure. 

When  the  cement  has  set  perfectly  hard,  the  surplus  around  the 
edges  should  be  removed.  In  collar  or  cap  crowns  the  extreme  edges 
of  the  gold  of  the  collar  or  cap  should  be  given  a  final  burnishing,  but 
force  should  be  avoided,  as  tending  to  injure  the  cement  under  the  col- 
lar. A  fine-pointed  instrument  and  floss  silk  should  be  passed  between 
and  around  the  teeth  to  remove  any  particle  of  the  superfluous  cement, 
and  finally  the  parts  should  be  syringed  with  tepid  water.  An  applica- 
tion may  be  made  of  a  saturated  solution  of  aristol  and  oil  of  cloves  with 
cotton  twisted  on  the  point  of  a  probe  to  relieve  pain  and  allay 
irritation. 

The  patient  should  be  requested  to  call  in  a  few  days  so  that  an 
examination  may  be  made  to  see  if  any  particles  of  the  cement  were 
overlooked.  Cleansing  at  this  time  facilitates  the  healing  of  the  gum 
around  the  edge  of  a  collar.  Care  in  such  details  tends  to  prevent  an 
inflamed  appearance  and  recession  of  the  gum  often  seen  around  crowns, 
and  also  insures  a  satisfactory  result  to  the  patient  and  commendation 
to  the  dentist. 

Gutta-Percha 

The  fact  that  recent  improvements  in  oxyphosphate  cement  have 
rendered  it  so  dense  and  hard  that  crowns  and  bridges  cemented  with 
it  are  so  difficult  to  remove  they  are  generally  destroyed  beyond  re- 


262 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


placement  or  repair,  has  prompted  an  endeavor  in  the  use  of  gutta- 
percha alone  or  in  combination  with  oxyphosphate. 

Gutta-percha  will  allow  the  work  to  be  removed  generally  intact, 
although  after  a  time  it  does  not  soften  as  easily  as  when  it  was  applied. 
Its  lack  of  rigidity  confines  its  use  to  crowns  and  bridges  that  rest 
steadily  on  their  foundation  and  require  the  gutta-percha  only  as  a 
medium  of  attachment.  The  slightest  vibration  of  a  cemented  cap  or 
crown  on  its  foundation  will  more  or  less  admit  the  permeation  of 
agents  which  will  result  in  the  dentin  and  gutta-percha  gradually  be- 
coming infected  and  the  attachment  of  the  gutta-percha  impaired. 
Oxyphosphate  combined  with  gutta-percha  may  be  utilized  in  many 
instances  to  overcome  this  difficulty. 

One  of  the  greatest  objections  to  the  use  of  gutta-percha  is  its 
refractory  behavior  in  application,  as  it  cannot  be  rendered  more  than 


Pig.  507. 

semi -plastic  with  heat  and  accordingly  is  difficult  to  manipulate  as  a 
cement.  Gutta-percha  will  adhere  to  a  heated  metallic  surface  but 
does  not  adhere  as  well  proportionately  to  tooth  structure. 

The  pink  base-plate  gutta-percha  or  gutta-percha  of  a  similar 
character  is  the  form  most  used  to  cement  crowns  and  bridges.  This 
form  being  generally  accepted  as  the  most  suitable,  similar  preparations 
that  can  be  more  easily  manipulated  have  been  introduced. 

Method  of  Cementing  with  Gutta-Percha  or  Gutta-Percha  Cement. 
The  description  given  will  apply  to  both  gutta-percha  and  gutta- 
percha cement,  but  the  latter  will  be  found  much  easier  of  manipula- 
tion. 

First.     Clean  perfectly  each  post  and  the  inside  of  each  cap. 

Second.  Place  the  cement-heater  (Fig.  507)  on  a  support  over  a 
Bunsen  flame,  remove  the  handle,  and  heat  until  a  drop  of  water  placed 
on  the  surface  will  instantly  boil  and  be  evaporated.  Insert  the  handle, 
remove  the  cement  heater  and  place  it  on  a  small  asbestos  pad,  or  a 


CEMENTATION  OF  CROWN-  AND  BRIDGE-WORK 


263 


couple  of  instruments  laid  upon  a  table,  and  again  remove  the  handle; 
or  use  a  How  gutta-percha  heater  (Fig.  508). 

Third.  Place  the  crown  or  bridge  in  a  slot  in  the  cement  heater, 
or  on  the  surface  of  the  How  gutta-percha  heater.  Heat  a  spatula 
(Fig.  509  in  miniature)  and  place  the  requisite  amount  of  gutta-percha 
on  the  gutta-percha  cement  heater  (A  Fig.  507)  or  on  the 
central  section  of  the  How  gutta-percha  heater.  If  gutta- 
percha cement  is  used,  manipulate  it  with  a  hot  spatula 
and  it  will  immediately  assume  a  plastic  consistence.     To 


Fig.  508. 


Pig.  509. 


apply  either  the  gutta-percha  or  the  cement,  steady  the  crown  or 
bridge  with  tweezers  on  the  slab  or  in  the  slot  of  the  cement  heater, 
or  remove  and  hold  in  a  napkin  with  the  fingers.  Reheat  when 
necessary  and  return  it  to  the  heater  when  the  gutta-percha  has  been 
applied. 

The  gutta-percha  or  cement  should  be  applied  with  the 
hot  spatula  a  very  little  at  a  time  as  a  surplus  will  not 
press  out  like  oxyphosphate.  In  the  case  of  collar 
crowns  the  proper  and  simplest  method  is  to  first  measure 
the  amount  of  gutta-percha  or  cement  required. 

Method  of  Measuring  Gutta-Percha. — This  is  easily  done  by  first 
placing  a  little  of  the  gutta-percha  or  cement  on  the  sides  of  the  in- 
terior of  the  collar  of  a  cap  or  of  a  gold  crown,  as  shown  in  section  at 
A,  A,  Fig.  510,  adjusting  the  work  in  exact  position  in  the  mouth  on  the 
wet  natural  teeth  by  pressure  and  occlusion  of  the  antagonizing  teeth, 
and  then  instantly  removing.  The  saliva  on  the  teeth  will  prevent 
adhesion  of  the  gutta-percha.     The  surplus  on  the  sides  will  be  pushed 


Fig.  510. 


264 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


to  the  bottom  of  the  cap  and  when  the  cap  is  removed  will  show  the 
impression  of  the  natural  tooth,  as  illustrated  in  Fig.  511,  Any 
vacancy  at  the  point  B  in  the  bottom  of  the  cap  will  very  accurately 
indicate  the  deficiency.     Next  wash  the  saliva  out  of  the  cap  with  a 


Fig.  511. 


syringe  full  of  water,  rinse  with  alcohol  by  pouring  in 
a  few  drops,  and  place  the  work  on  the  heater  and 
wait  until  the  alcohol  has  evaporated,  then  apply  the 
required  additional  gutta-percha  or  cement.  A  small 
straight,  blunt-pointed  instrument — ^such  as  a  broken 
excavator — is  useful  to  carry  small  pieces  or  pellets 
to  the  bottom  or  corner  of  a  cap. 

To  distribute  the  gutta-percha  or  cement  in  the 
case  of  a  Richmond  crown,  place  a  little  on  the  inner 
edge  of  the  collar  as  indicated  at  S,  S,  Fig.  512.  By  one  or  more  in- 
sertions, the  necessary  quantity  for  the  remainder  of  the  surface  of 
the  crown  can  be  accurately  determined.  Next  and  last  apply  the 
gutta-percha  on  the  post.  Should  any  vacuoles  exist  they  will  be  filled 
by  the  film  of  oxyphosphate  applied  to  the  surface  of  the 
crown  or  bridge  abutments  in  the  final  act  of  cementation. 
In  any  form  of  crown  with  a  closely-fitting  post  with- 
out a  collar,  first  measure  the  quantity  of  cement  required 
at  the  base  or  floor,  by  placing  the  gutta-percha  or  cement 
on  that  part,  inserting  the  crown  in  the  mouth  and  remov- 
ing before  applying  to  the  post. 

To  Apply  Gutta-Percha  in  the  Form  of  a  Film  over  a 
Surface. — Place  a  little  of  the  gutta-percha  or  cement  in 
the  concavity  formed  in  the  bottom  of  a  cup  or  jar,  add 
chloroform,  mix  with  a  camel's-hair  brush  and  apply  the  solution 
evenly  over  each  post  and  on  the  inner  surface  of  each  metallic  cap. 
Next  place  the  crown  or  bridge  in  the  slot  of  the  cement  heater  to 
evaporate  the  chloroform. 

As  only  a  very  small  quantity  of  gutta-percha  will  in- 
tervene between  a  close-fitting  post  or  metalhc  cap  and  the 
tooth  structure,  the  adjustment  is  more  easily  effected  in 
the  mouth  when  the  cement  is  evenly  placed  over  the  sur- 
face as  desciibed. 
The  best  possible  adhesion  of  gutta-percha  to  metal  is  secured  by 
slightly  scratching  intersecting  lines  on  the  posts  and  inner  surface  of 
metallic  crowns,  in  the  form  shown  in  Fig.  513,  with  a  fine  sharp-point- 
ed instrument  previous  to  the  process  of  cementation.  In  open-faced 
crowns  this  process  applied  to  the  inner  surface  of  a  strip  of  the  metal 
traversing  the  cervical  portion  of  the  labial  face,  very  materially  aids 
in  the  retention  of  the  gutta-percha. 


Pig.  512. 


Fig.  513. 


CEMENTATION  OF  CROWN-  AND  BRIDGE-WORK  265 

When  the  gutta-percha  or  cement  has  been  measured,  the  crown 
or  bridge  is  left  on  the  cement-heater  until  ready  to  be  cemented  in  the 
mouth. 

Gutta-percha  does  not  adhere  to  tooth-structure  as  well  as  to  metal. 
For  permanent  insertion  to  secure  a  reliable  adhesion  of  the  gutta- 
percha, varnish  the  root  or  tooth  with  a  very  thin  film  of  oxyphosphate. 
This  is  best  done  by  mixing  a  portion  of  oxyphosphate  to  the  consist- 
ence of  a  very  thin  cream  and  applying  it  with  a  small  stiff  camel's-hair 
brush  on  the  sides  of  the  crown  or  root.  As  the  cap  or  caps  are  brought 
to  position  the  pressure  will  be  sufficient  to  make  the  oxyphosphate 
adhere  securely  to  the  tooth-structure  and  the  gutta-percha.  The  oxy- 
phosphate also  excludes  air  by  creating  a  slight  surplus. 

To  Cement  the  Crown  or  Bridge.— Syringe  the  tooth  or  teeth  to  be 
crowned  with  water,  protect  from  saliva,  bathe  with  alcohol  applied 
with  a  pellet  of  cotton,  dry  and  evaporate  all  moisture  with  a  hot-air 
syringe.  Mix  the  oxyphosphate  and  apply  it  quickly  as  described, 
then  immediately  remove  the  crown  or  bridge  from  the  cement 
heater,  and  when  it  has  cooled  to  a  point  that  will  permit  it  to 
be  held  between  the  fingers,  instantly  place  and  press  it  to 
position  in  the  mouth,  and  in  the  case  of  a  gold  crown  or 
bridge  have  the  patient  forcibly  occlude  the  teeth  and  hold 
them  firmly  in  position  until  the  oxyphosphate  cement  has 
set,  when  the  surplus  at  the  edges  can  be  removed. 

For  Temporary  Insertion. — ^Instead  of  using  oxyphosphate 
as  described,  varnish  the  root  or  tooth  with  a  thin  coating  of  fig.  514. 
chloro-gutta-percha  or  in  the  use  of  gutta-percha  cement,  with 
the  adhesive  fluid  that  comes  with  it.  The  gutta-percha  can  be  chilled 
with  cold  water  from  a  syringe.  It  is  hardened  to  a  certain  extent 
by  the  application  of  cold  but  does  not  acquire  its  greatest  density 
for  some  time. 

Requirements  for  Success.— For  the  successful  use  of  gutta-percha, 
crown-  and  bridge-work  must  be  constructed  with  that  intention,  and 
every  detail  connected  with  the  cementation  carefully  carried  out. 
Richmond  crowns  should  have  long  substantial  posts,  either  round  or 
of  the  Logan  pattern,  properly  fitted  to  the  canal  (Fig.  514).  If  the 
canal  is  enlarged  from  some  cause  or  is  of  irregular  form,  after  closing 
the  foramen  with  gutta-percha,  taper  the  end  of  the  post  and  fit  the 
point  deeply  in  the  canal,  varnish  the  post  all  over  with  a  film  of 
chloro-percha,  evaporate  the  chloroform,  fill  the  canal  with  oxyphos- 
phate and  insert  the  post.  When  the  oxyphosphate  has  set,  heat  the 
post  or  crown,  withdraw  it,  and  wipe  out  the  canal  with  a  wisp  of  cot- 
ton saturated  with  chloroform,  to  remove  the  gutta-percha  adhering 


266  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

to  the  oxyphosphate.  This  furnishes  a  close-fitting  socket  for  the 
post.  For  all-gold  crowns,  badly  decayed  teeth  should  have  their 
sides  restored  with  amalgam  or  gold  inlays.  Roots  for  gold  crowns 
should  have  posts  or  screws  cemented  in  them  and  be  shaped  up  with 
amalgam,  as  shown  in  Pigs.  187  and  188.  Short  gold  crowns  support- 
ing bridge-work  require  one  or  two  pins  that  will  fit  in  small  holes  drilled 
in  the  deep  fissure  of  the  occlusal  surface,  as  shown  in  Fig.  515  or  in  a 
slot  or  cavity  in  the  side  extending  nearl}.  to  the  cervical  margin  as 
illustrated  in  Fig.  516.  A  pin,  no  matter  how  short,  inserted  in  the 
center  of  the  occlusal  surface  of  an  all-gold  crown  steadies  the  crown 

^^^^^  and  thus  assists  in  its  retention.  Rolling  wire  under  the 
fflHIln  flat  side  of  a  file  before  using  in  the  construction  will 
FT JJ  roughen  it  and  offer  a  better  surface. 

Pjg  Favored  by  proper  construction,  many  cases  of  bridge- 

work  can  be  reliably  cemented  with  gutta-percha.  Among 
the  exceptions  are  very  short  caps  or  open-faced  crowns  in  which  pins 
or  a  post  cannot  well  be  inserted  and  which  in  supporting  bridge-work 
are  subjected  to  a  great  strain  or  pressure  in  occlusion;  also  all  cases 
of  extension  bridge-work. 

Oxyphosphate  in  Combination  with  Gutta-Percha  or  Gutta-Percha 
Cement. — Gutta-percha  or  gutta-percha  cement  may  be  used  in  com- 
bination with  oxyphosphate  by  applying  the  gutta-percha  scantily, 
removing  it  from  the  entire  cavo-edge  or  border  of  the  cap  and  in  the 
final  insertion  of  the  work,  coating  the  natural  crowns  or 
roots  with  oxyphosphate  applied  in  sufficient  quantity 
with  a  small  brush  to  fill  any  vacancies.  This  method  will 
result  in  the  presence  of  a  coating  of  oxyphosphate  over  the 
surface  of  the  tooth  or  root  and  a  larger  proportion  of  pic.  516. 
gutta-percha  over  the  cavo-surface  of  the  cap,  and  will  in- 
crease the  security  of  attachment  and  the  gutta-percha  which  will 
simplify  removal.  (For  the  removal  of  crowns  and  bridges  cemented 
with  gutta-percha,  see  Part  IV,  Chapter  VIII.) 

Silicate  Cement. — ^This  cement  in  an  improved  form  is  commencing 
to  take  the  place  of  oxyphosphate  of  zinc  for  cementation  of  porcelain 
inlays,  as  it  closely  resembles  porcelain  and  is  less  soluble  than  the 
oxyphosphate. 

Amalgam. — The  use  of  amalgam  for  purposes  of  cementation  has 
been  superseded  by  the  oxphosphate  and  silicate  cements. 


n 


PART  IV 
BRIDGE-WORK 


INTRODUCTION 

SCIENTIFIC  MECHANICAL  PRINCIPLES — DENTAL  BRIDGE-WORK — ANTI- 
QUITY— PRIMITIVE  METHODS — MODERN  LITERATURE — MODERN  ME- 
THODS— ADVANTAGES — OBJECTIONABLE  FEATURES — PROPHYLAXIS 
— IMPARTIAL    CONSIDERATION — FORMS    OF    BRIDGE    CONSTRUCTION 

Scientific  Mechanical  Principles 

A  bridge  is  a  structure  that  spans  a  space  and  is  supported  by  solid 
bases  termed  abutments  and  piers.  The  abutments  are  located  at 
each  end  of  the  structure  and  the  piers  at  intervals  between  the  abut- 
ments. A  bridge  is  designed  to  support  not  only  its  own  weight  but 
additionally  such  pressure  and  stress  as  its  structural  capacity  is 
calculated  to  bear. 

A  bridge  consists  of  a  substructure  and  a  superstructure.  The 
substructure  consists  of  the  foundations  and  the  superstructure  of  the 
portion  that  rests  on  the  foundations  and  spans  the  space. 

Bridges  are  classified  as  of  five  forms;  Arch  bridges,  in  which  the 
pressure  is  vertical  and  outward  against  the  terminal  abutments;  Truss 
bridges,  in  which  one  girder  or  several  connected  girders  form  a  rigid 
span  between  the  abutments;  Suspension  bridges,  in  which  platforms 
are  supported  by  cables  that  pass  over  abutment-towers,  the  ends  of 
the  cables  being  anchored  in  the  ground;  Pontoon  bridges,  formed  of 
platforms  resting  on  boats  anchored  in  a  stream;  Cantilever  bridges, 
formed  of  two  trusses,  the  central  section  of  each  truss  resting  on  a  pier, 
with  the  longer  ends  of  the  trusses  weighted  and  anchored  in  the  shore, 
and  the  shorter  or  river  ends  extended  so  they  meet. 

Dental  Bridge-work 

In  dental  prosthesis  bridge-work  is  the  utilization  of  natural  teeth 
or  roots  as  the  substructure-abutments  and  of  artificial  teeth  as  the 
superstructure-spans. 

Antiquity. — The  artificial  repair  of  the  loss  of  a  portion  of  the  teeth 
by  bridging  the  vacant  spaces  with  substitutes,  supported  in  position 
by  means  of  their  attachment  to  adjoining  or  intervening  natural 
teeth,  is,  as  we  have  seen  in  the  introduction,  of  ancient  origin,  having 
been  practiced  long  before  plates  came  into  use. 

269 


270 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Primitive  Methods. — Originally  the  application  and  mechanical 
construction  of  such  dentures  was  of  a  most  primitive  character,  and  as 
the  attachments  were  simply  ligatures,  or  clasps  of  gold,  the  teeth  were 
more  ornamental  than  useful.  Figs.  517,  518  and  519  illustrate  some 
antique  methods.^  Fig.  517  is  an  illustration  of  a  specimen  of  ancient 
Phoenician  dentistry.     Fig.  518  is  that  of  one  of  the  Etruscan  age, 


Fig.  S17. 


Fig.  51 


dating  about  500  B.  C.  Fig.  519  gives  a  view  of  the  same  denture 
inverted. 

Dentures  constructed  on  the  bridging  plan  by  various  methods 
have  been  occasionally  employed  from  the  earliest  days  of  modern 
dentistry,  although  until  recent  years  the  method  has  not  obtained 
general  recognition  or  been  extensively  practiced  as  a  system. 

Modem  Literature. — Dental  literature  presents  bridging  operations 
as  described  by  Dubois  de  Chemant  in  1802;  J.  B.  Gariot  in  1805; 


Fig.  519. 


Pig.  520. 


C.  F.  De  la  Barre  in  1820;  Dr.  S.  S.  Fitch  in  1829;  William  Imrie  in 
1834;  J.  Patterson  Clark  in  1836  (Fig.  520)  and  Dr.  W.  H.  Dwindle 
in  1856.  Figs.  521  and  522  are  copies  of  illustrations  in  Dr.  Fitch's 
work,  published  in  New  York  in  1829,  and  Fig.  523,  one  from  a  trans- 
lation of  F.  Maury's  work  in  1843.  ^^  187 1  the  bridging  process  or 
bridge  principle  was  again  brought  to  notice  by  a  patent  applied  for 
in  England  by  Dr.  B.  J.  Bing,  of  Paris,  for  an  improved  means  of  sup- 
1  See  "Independent  Practitioner,"  Vols.  VI  and  VIT,  " Evidences  of  Prehistoric 
Dentistry,"  by  J.  G.  Van  Marter,  D.  D.  S.,  Rome,  Italy.  Figs.  517,  518  and  519 
are  copies  of  the  illustrations  of  specimens,  the  first  of  which  is  represented  as  being 
in  the  museum  of  the  Louvre,  Paris,  France,  and  the  second  in  the  Corneto  Museum, 
Corneto,  Italy. 


INTRODUCTION 


271 


porting  and  securing  a  bridge  by  anchoring  with  cement  or  filHngs, 
clasps  or  bars,  extending  from  it  into  holes  formed  in  the  adjoining  teeth 
(Fig.  524).  The  system  was  also  practiced  by  the  late  Dr.  M.  H.  Webb 
and  is  described  in  his  "  Notes  on  Operative  Dentistry." 

Modem  Methods. — The  facilities  afforded  by  the  artificial  crown- 
work  now  in  vogue  for  supporting  and  securing  bridge  dentures  have 
caused  a  revival  of  the  system  in  an  improved  form,  now  termed  "Bridge- 
Work,"  in  which  artificial  crowns  cemented  to  natural  teeth  or  roots  are 


Pig.  521. 


Fig.  522. 


employed  as  abutments  to  support  artificial  teeth  which  span  or  bridge 
the  space  between  them.  These  bridges  are  so  devised  in  the  best 
methods  that,  while  supplying  the  patient  with  the  means  of  masti- 
cating food,  the  cleanliness  of  the  denture  is  also  provided  for. 

Advantages. — Ordinarily  bridge-work  is  immovably  cemented  in 
position.     The  claims  set  up  in  its  favor  are  as  follows: 

First. —  The  perfect  replacement  of  lost  teeth  by  artificial  substi- 
tutes without  the  use  of  a  plate. 


Pig.  523. 


Fig.  524. 


Second. — The  absence  of  any  mechanical  contrivance  to  interfere 
with  the  tongue  in  articulation. 

Third. — The  functions  of  the  sense  of  taste  are  more  perfectly 
performed  and  a  healthy  condition  of  the  tissues  preserved  because 
the  gums  and  palate  are  not  covered  over  with  a  plate. 

Fourth. — The  soHdity  and  security  of  the  denture  at  all  times,  both 
in  speech  and  mastication. 

Fifth. — The  weight  of  the  denture  and  the  strain  of  mastication 
are  proportionately  distributed  over  the  natural  teeth,  which  are  better 
suited  to  sustain  them  than  the  contiguous  alveolar  surfaces. 


272  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Sixth. — Its  special  adaptation  to  the  replacement  of  single  teeth 
or  of  a  small  number  of  teeth,  where  bridge-work  is  usually  superior 
to  any  other  device. 

Seventh. — While  all  operations  performed  for  the  restoration  of  lost 
teeth,  like  other  remedial  operations,  are  temporary  rather  than  per- 
manent in  their  results,  bridge- work  as  regards  permanency  takes  equal 
rank  with  any  other  operative  procedure. 

Objectionable  Features. — The  following,  on  the  other  hand,  are 
the  objections  raised,  particularly  so  against  cemented  unremovable 
bridge-work  as  generally  constructed. 

First. — It  fails  to  restore  the  contour  of  the  soft  tissues  above  the 
bridge,  as  in  cemented  bridges  artificial  gums  cannot  properly  be  used. 

Second. — The  slots  under  the  artificial  teeth  fill  with  particles  of 
food. 

Third. — The  speech  and  comfort  of  the  wearer  are  often  affected 
by  these  slots,  especially  when  under  the  front  teeth. 

Fourth. — The  natural  teeth  employed  as  abutments  are  permanently 
mutilated  by  the  process  of  crowning. 

Fifth. — ^An  extensive  bridge  made  of  gold,  when  immovable,  cannot 
possibly  be  kept  perfectly  clean,  as  the  metal  will  gradually  tarnish  in 
parts  out  of  reach  of  the  brush  and  offensive  matter  will  gather  on  its 
surface  and  in  its  interstices  and  become  septic. 

Sixth. — In  cases  where  it  becomes  necessary  to  temporarily  remove 
a  cemented  bridge  for  the  purpose  of  repair,  or  because  of  disease  in 
the  teeth  that  support  it,  the  operation  is  difficult  and  the  bridge  is 
usually  injured  so  as  to  unfit  it  for  reinsertion. 

Seventh. — The  teeth  that  support  a  bridge,  whether  fixed  or  re- 
movable, are  required  to  bear  more  force  and  pressure  than  nature 
intended — where  the  piece  is  large,  many  times  more — and  at  no  time 
can  rest  be  given  the  abutments  or  the  contiguous  parts.  Thus,  in 
a  piece  of  bridge-work  of  fourteen  teeth  supported  by  caps  or  crowns 
on  four  to  six  natural  teeth,  each  one  of  the  natural  teeth  may  have  to 
bear  two  or  more  times  the  strain  in  supporting  the  weight  of  the  den- 
ture and  the  force  of  mastication  that  was  intended.  The  ultimate 
result  is  evident  to  anyone  who  is  experienced  in  dental  practice,  and 
unless  the  anatomical  conditions  are  most  favorable,  the  usefulness 
and  durability  of  such  work  is  liable  to  be  limited  in  character,  consider- 
ing the  time,  trouble  and  great  expense  attending  its  construction. 

Prophylaxis. — The  most  forcibly  urged  objection  advanced  against 
cemented  unremovable  bridge- work  is  that  it  is  uncleanly  and  that  a 
septic  condition  supervenes  which  in  time  becomes  infectious. 

Small  bridges  comprising  only  a  few  teeth  are  much  less  open  to 


INTRODUCTION  273 

this  criticism  than  large  ones.  The  proposition  depends  piincipally  on 
judgment  respecting  the  suitability  of  a  case  for  bridge-work,  the  form 
of  bridge  applied,  and  the  skill  employed  in  its  constructive  details, 
especially  the  continuity  of  all  its  parts. 

In  properly  applied  and  constructed  bridge-work,  uncleanliness  is 
usually  attributable  to  lack  of  knowledge  on  the  part  of  the  patient  of 
proper  methods  of  prophylaxis,  or  neglect. 

Consequently,  the  tendency  is  to  confine  the  application  of  bridge- 
work  to  favorably  positioned  small  cases  and  to  make  large  ones 
removable. 

Such  are  the  arguments  that  have  been  put  forth  for  and  against 
bridge-work;  and  yet,  whatever  may  be  urged  against  it,  its  advantages 
are  recognized  by  a  majority  of  the  profession,  including  accepted 
authorities,  some  practitioners  even  going  so  far  as  to  proclaim  it  the 
only  true  method  for  the  insertion  of  partial  dentures. 

Impartial  Consideration. — Judged  impartially,  bridge-work  has 
many  advantages  when  practiced  by  experts  who  properly  construct 
and  apply  it.  Without  doubt  it  has  been,  and  is  still,  and  will  be 
abused.  Bridges  have  been  inserted  where  the  support  was  insufficient 
or  the  construction  was  wrong  in  principle  or  faulty  from  lack  of  skill. 
Moreover,  bridge-work  is  yet  passing  through  the  experimental  period 
when  failures  are  apt  to  appear  more  prominently  than  successes. 
The  chronicles  of  dental  literature,  however,  offer  in  this  respect  only 
a  repetition  of  the  historical  difficulties  that  attend  all  new  methods  in 
the  arts. 

Forms  of  Bridge  Construction 

Bridge-work  is  constructed  either  Fixed,  Detachable  or  Removable. 
A  fixed  bridge  is  permanently  cemented;  a  detachable  bridge  can  be 
detached  by  the  dentist,  and  a  removable  bridge  by  the  patient.  Of 
these  three  forms  of  bridges  there  are  several  subdivisions  differing 
in  application,  details  of  construction  and  materials,  each  of  which  will 
be  separately  discussed  in  this  and  the  succeeding  section. 


18 


CHAPTER  I 
CONSTRUCTION  OF  BRIDGE- WORK 

PRINCIPLES  INVOLVED — ABUTMENTS,  RETENTIVE  AND  SUPPORTING — 
OCCLUSION — THE  ARTISTIC  AND  ESTHETIC — PORCELAIN  FACINGS 
AND  TEETH  FOR  DUMMIES — -CLASSIFICATION  OF  BRIDGE-WORK — 
PREPARATION  OF  THE  SUPPORTING  TEETH  OR  ABUTMENTS — CON- 
STRUCTION— ^lAIPRESSIONS  AND  MODELS — SELECTION  AND  ADJUST- 
MENT OF  ARTIFICIAL  TEETH — ^BACKINGS — OCCLUSAL  CUSP-CAPS — 
INVESTING  THE  BRIDGE — SOLDERING — FINISHING — ^VARIATIONS  IN 
METHOD  OF  CONSTRUCTION — CONSTRUCTION  IN  SECTIONS — SOLDER- 
ING ON  THE  MODEL — CORRECTION  OF  WARPING — ^ADJUSTMENT  AND 
INSERTION — CONSTRUCTION  OF         BRIDGE-WORK  EMBRACING 

BOTH  SIDES   OF  THE  MOUTH — CONSTRUCTION  OF   SMALL    PIECES    OF 
BRIDGE-WORK 

To  those  who  are  properly  informed  in  mechanical  dentistry  and 
versed  in  metal  and  crown-work,  bridge- work  does  not  present  extreme 
difl&culty.  The  foundations  or  abutments,  that  is,  the  teeth  or  roots  on 
which  the  bridge  will  rest,  are  first  to  be  considered,  due  respect  being 
paid  to  the  mechanical  principles  controlling  the  leverage  and  the  force  of 
occlusion  in  mastication. 

Principles  Involved 

The  proper  selection  of  abutments,  and  the  type  and  form  of  con- 
struction of  bridge-work  are  fundamentally  dependent  on  a  knowledge 
of  and  application  of  the  principles  of  the  sciences  of  anatomy,  physi- 
ology, orthodontia,  metallurgy  and  mechanics,  oral  surgery  and  hygiene. 
Failure  to  comply  with  the  principles  and  requirements  of  these  sciences 
will  invariably  partially  if  not  entirely  destroy  the  functional  effici- 
ency and  permanency  of  the  operation,  and  establish  conditions  detri- 
mental to  the  health  of  the  patient. 

Abutments,  Retentive  and  Supporting 

The  abutments  in  cemented  bridge- work  are  divided  into  two  classes, 
retentive  and  supporting.  A  retentive  abutment  retains  as  well  as 
supports  a  bridge.  A  supporting  abutment  supports  a  bridge  but  does 
not  retain  it  in  position. 

274 


CONSTRUCTION  OF  BRIDGE-WORK  275 

Mechanics 

In  the  selection  of  abutments  the  amount  of  stress  that  can  be  borne 
by  the  different  teeth,  individually  and  collectively,  according  to  their 
position  and  condition  of  health,  should  be  carefully  calculated.  A 
relative  estimate  of  the  ability  of  different  teeth  to  resist  stress  when 
used  as  abutments  would  place  them  in  the  following  order: 

(a)  First  Molars,  (b)  Second  Molars,  (c)  Cuspids,  (d)  Bicuspids, 
(e)  Central  Incisors  (d)  Lateral  Incisors. 

In  dental  bridge-work  the  stress  on  the  abutments  is  both  direct 
and  lateral,  divided  proportionately  according  to  their  position  and  the 
character  of  the  occlusion.  As  a  rule  the  force  upon  the  incisors  and 
cuspids  in  occlusion  will  be  directed  outward  on  the  upper  and  inward 
on  the  lower.  Therefore  the  tendency,  when  any  of  these  teeth  or  roots 
support  a  bridge,  is  to  gradually  press  them  and  the  bridge  out  of  line 
in  these  directions. 

In  the  case  of  molars  the  force  is  mostly  direct  in  an  apical  direction 
in  a  normal  occlusion,  with  some  lateral  pressure  caused  by  contact  of 
^  the  cusps  in  the  movement  of  the  mandible  in  mastication. 

Occlusion 

In  the  planning  of  bridge-work  there  is  no  other  factor  on  which 
the  future  success  of  the  bridge  as  a  serviceable  and  lasting  denture 
depends  so  much  as  a  properly  arranged  occlusion.  Pressure  on  abut- 
ment teeth  should  be  placed  as  nearly  as  possible  in  line  with  the  axis 
of  their  crowns  and  roots,  and  occlusal  surfaces  of  both  abutment  crowns 
and  dummies  should  be  positioned  and  shaped  with  this  object  in 
view.  The  greater  the  proportion  of  the  vertical  stress  to  the  antero- 
posterior or  lateral,  the  greater  the  probability  that  two  or  more 
abutments  combined  will  be  able  to  withstand  the  stress  placed  upon 
them  in  occlusion  and  mastication,  and  the  longer  is  the  term  of  their 
usefulness  assured. 

In  the  construction  of  bridge- work  the  occlusal  surfaces  of  abut- 
ments should  be  given  normal  dimensions,  but  the  cusps  should  be  so 
shaped  as  to  minimize  stress  in  mastication  in  the  lateral  movements 
of  the  mandible  when  brought  into  contact  with  the  cusps  of  antagoniz- 
ing teeth.  Short  cusps  cause  less  lateral  stress  than  long  ones.  This 
point  should  be  borne  in  mind,  not  only  in  relation  to  the  occlusal  cusps 
of  abutment  crowns,  but  especially  in  regard  to  those  of  dummies,  the 
occlusal  surfaces  of  which  should  be  additionally  favored  by  being 
made  slightly  narrower  bucco-lingually  than  the  abutments  and  very 
narrow  when  there  are  no  antagonizing  teeth. 


276  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

A  normal  line  of  occlusion  of  the  teeth  favors  the  construction  and 
use  of  bridge-work.  When  such  a  condition  does  not  exist,  the  defect 
should  be  remedied  as  much  as  possible  by  trimming  the  incisal  edges 
and  occlusal  surfaces  of  such  antagonizing  teeth  as  are  out  of  line  and 
restoring  as  far  as  may  be  the  line  of  the  occlusal  plane. 

Procedure  under  such  conditions  is  illustrated  in  Fig.  525,  a  case  in 
which  the  occlusion  is  not  uniform.  The  dotted  line  indicates  how 
much  of  the  teeth  requires  to  be  removed  to  remedy  the  defect  and 
render  the  occlusion  favorable  to  the  insertion  of  bridge- work  that  will 
permit  proper  performance  of  the  masticatory  function.  Sometimes 
the  removal  of  a  pulp  may  become  necessary  in  order  to  effectually 
shorten  a  tooth  which  has  become  excessively  elongated. 


Pig.  525. 

The  Artistic  and  Esthetic 

In  dental  prosthesis  bridge- work  does  not  always  enable  the  operator 
to  improve  the  appearance  of  the  patient  as  well  as  it  can  be  done  with 
plate-work.  The  teeth  or  roots  present  that  have  to  be  utilized  as 
abutments  may  not  be  in  normal  position  or  occlusion  and  the  labial 
surfaces  of  teeth  used  as  abutments  with  inlay  attachments  or  open- 
face  crowns,  may  be  more  or  less  disfigured  by  erosion  or  abrasion. 
Deep  depressions  caused  by  absorption  of  the  alveoli  cannot  be  entirely 
concealed  with  fixed  bridge-work,  as  the  utilization  for  the  purpose  of 
metal  or  vulcanite  and  even  porcelain,  except  to  a  very  small  extent, 
would  not  be  sanitary.  Such  restoration  demands  the  use  of  a  remov- 
able bridge  or  a  plate.  These  conditions,  also  that  of  abnormally  large 
or  small  spaces  requiring  to  be  filled  with  only  a  certain  number  of 
artificial  teeth,  tax  the  ingenuity  and  mechanical  skill  of  the  operator. 
Correct  arrangement  and  harmony  of  form  should  prevail  wherever 
possible. 

Porcelain  Facings  and  Teeth  for  Dummies 

Facings  and  teeth  should  be  selected  that  in  form  and  shade  will 
not  appear  artificial  in  contrast  with  adjoining  natural  teeth.     A  dis- 


CONSTRUCTION  OF  BRIDGE-WORK  277 

play  of  gold,  especially  in  connection  with  the  eight  anterior  teeth, 
should  be  avoided  wherever  possible.  The  truly  artistic  and  esthetic 
demand  a  restorative  operation  that  will  pass  unnoticed  to  an  observer. 

Classification  of  bridge-work 

A  simple  bridge  is  unilaterally  straight  in  alignment,  or  nearly  so, 
and  supports  but  one  or  two  teeth  or  dummies. 

A  compound  bridge  is  unilaterally  curved  in  alignment,  is  supported 
by  end  abutments  and  intervening  piers,  and  replaces  from  three  to 
five  teeth. 

A  complex  bridge  is  bilaterally  curved,  crossing  the  median  line, 
having  the  necessary  abutments  and  intervening  piers.  It  replaces 
from  four  to  ten  teeth. 

Under  normal  conditions  the  rules  that  generally  govern  the  number 
and  position  of  the  teeth  or  roots  required  as  foundations  for  bridges 
are  as  follows: 

One  central  crown  or  root  as  a  retentive  abutment  will  support  the 
adjoining  central  with  the  aid  of  a  lug  resting  on  or  anchored  in  an 
inlay  or  filling  in  the  lateral  as  a  supporting  abutment.  A  cuspid  will 
support  a  central  and  lateral  with  retentive  abutment  on  the  other 
central. 

Two  central  crowns  will  support  the  laterals  with  the  aid  of  support- 
ing abutments  in  the  cuspids.  . 

The  cuspids  alone  or  with  the  additional  aid  of  a  central  pier  or 
inlay  or  of  lugs  securely  anchored  in  the  bicuspids  will  support  the 
incisors. 

One  molar  or  bicuspid  on  one  side  and  a  bicuspid  or  molar  on 
the  other,  and  two  reliable  piers  in  an  intermediate  position,  will 
support  a  bridge  between  them. 

One  first  or  second  molar  on  one  side  and  one  molar  on  the  other 
with  the  assistance  of  the  two  cuspids,  will  support  a  bridge  comprising 
the  arch  between  them;  termed  a  complex  bridge. 

Two  or  three  suitable  teeth  or  roots  on  one  side  of  the  mouth  can 
support  between  them  a  bridge  on  that  side.  The  cuspids  always 
afford  a  reliable  anterior  support. 

In  a  cuspid  anterior  bridge,  such  as  is  shown  in  Fig.  526,  its  outward 
curve,  especially  when  the  articulation  of  the  antagonizing  teeth  is 
close  and  deep,  causes  lateral  stress  or  leverage  in  excessive  proportion 
to  the  direct.  Such  a  dental  bridge  in  form  is  equivalent  to  a  curved 
truss  bridge,  which  in  principle  would  be  condemned  as  con- 
trary to  engineering  principles  unless  supported  by  at  least  one  cen- 
trally located  pier  to  rv-^lieve  the  lateral  stress  on  its  terminal  abutments. 


278 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


In  the  case  of  a  cuspid  anterior  bridge,  a  centrally  located  pier  not 
being  available,  the  bridge  should  be  made  removable,  with  a  saddle 
as  a  substitute;  or  the  cantilever  principle  should  be  employed  by  ob- 
taining support  distally  from  the  bicuspids.  Such  support  may 
be  obtained  for  this  bridge,  as  for  other  differently  located  bridges,  in  a 
variety  of  ways,  the  character  or  form  of  device  to  be  determined  by  the 
conditions  and  requirements  of  each  case. 

In  the  case  illustrated  in  Fig.  526,  when  the  adjoining  first  bicuspid 
has  a  vital  pulp,  either  a  partial  or  an  entire  gold  cap-crown  can  be 
placed  upon  it,  as  shown  at  CB,  Fig.  527,  or  an  MO  inlay  may  be 
inserted,  extended  across  the  occlusal  surface  with  the  distal  end  ad- 
ditionally secured  with  a  post,  as  shown  at  D.  Another  method  is  to 
insert  a  triangular  bar  with  the  end  bent  and  extended  as  seen  at  E. 
A  pulpless  tooth  admits  of  a  deep  extension  of  the  post  into  the  pulp- 
chamber. 


Fig.  526. 


Fig.  527. 


In  the  case  of  a  cuspid  anterior  cantilever  bridge  and  in  all  cases 
where  either  inlays  or  crowns  are  joined  together  as  abutments,  the 
construction  should  be  so  conducted  as  to  leave  the  interproximal  spaces 
open  and  free  to  insure  the  presence  of  the  gum  septa  in  a  normal  con- 
dition. In  a  compound  cuspid  anterior  and  second  bicuspid  bridge, 
the  four  incisors  and  two  first  bicuspids  being  replaced,  the  second 
bicuspid  abutment  crowns  act  as  cantilever  supports  and  usually  are 
reliable  anchorages.  In  a  cuspid  posterior  second  molar  bridge  car- 
rying the  two  bicuspids  and  the  first  molar,  the  cuspid  and  second  molar 
have  to  withstand  the  force  of  the  occlusion  of  five  teeth  and  the  cuspid 
lateral  stress  in  addition.  Such  a  bridge  is  best  made  of  the  removable 
saddle  type,  as  in  the  fixed  form  the  abutments  in  a  short  time  will 
become  impaired.  In  all  cases  where  there  is  an  extensive  span  between 
the  abutments,  a  removable  saddle  bridge-piece  is  the  most  suitable 
form  to  construct. 


CONSTRUCTION  OF  BRIDGE-WORK  279 

The  rules  given,  applied  to  these  cases,  will  enable  the  operator, 
governed  by  the  special  conditions  presented  in  each  individual  case, 
to  properly  select  and  decide  the  character  of  the  abutments  and  piers. 
The  relative  resistance  of  individual  teeth  and  the  conditions  respecting 
occlusion  are  here  given  as  a  general  guide,  but  several  contributing  fac- 
tors may  upset  any  plan  which  affords  no  scientific  basis  for  comparison. 

Selection  of  the  most  suitable  teeth  as  abutments  or  piers  in  bridge- 
work  operations  so  as  to  most  effectively  distribute  the  force  of  occlusion, 
will  assure  the  best  practical  results,  especially  as  regards  the  mainte- 
nance and  stability  of  the  abutments,  on  which  depends  the  durability 
of  the  work. 

Preparation  of  the  Supporting  Teeth  or  Abutments. — The  prepara- 
tion of  teeth  or  roots  to  support  a  bridge  is  the  same  as  for  ordinary 
crowns,  except  that  the  trimming  of  the  sides  and  the  reaming  of  the 
root-canals  of  the  various  anchorages  must  be  in  parallel  lines,  so  that 
the  collars  and  posts  of  the  crowns  will  move  readily  to  their  places  in 
he  adjustment  of  the  finished  bridge.     Teeth  or  roots  which  are  to  be 


Pig.  528. 

supplied  with  porcelain-faced  or  all-gold  cap-crowns  are  crowned  by 
some  of  the  methods  already  described.  In  the  first  stage  of  the  con- 
struction of  the  bridge,  the  roots  that  are  to  carry  porcelain-faced 
crowns  may  be  only  capped,  the  posts  being  soldered  and  allowed 
to  project  a  short  distance  beyond  the  caps. 

The  lines  of  the  crowns  of  teeth  or  root-canals  to  be  used  as  abut- 
ments or  supports  for  bridge-work  are  seldom  exactly  parallel.  This 
fact  should  be  borne  in  mind  and  receive  proper  consideration  in  their 
preparation.  When  one  of  the  bridge-supporting  teeth  tips,  or  when 
two  of  them  lean  toward  each  other,  the  tipping  side  or  sides  may  re- 
quire extensive  trimming,  while  the  other  side  or  sides  will  usually 
require  much  less.  This  is  finely  exemplified^  in  Fig.  528,  which 
represents  a  molar  and  cuspid  with  living  pulps.  The  cuspid  in  tipping 
forward  has  straightened  the  line  of  the  posterior  or  distal  side,  so  that 
it  requires  very  little  trimming.  The  portion  requiring  removal  at 
the  point  A,  will  be  regulated  to  some  extent  by  the  shape  given  the 
molar.     By  considerable  reduction  of  the  distal  side  of  the  molar  at  the 


28o 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


point  B  to  a  line  parallel  with  the  anterior  or  mesial  side  of  the  cuspid,  a 
form  is  given  to  both  teeth  which,  with  a  moderate  reduction  of  the 
anterior  or  mesial  side  of  the  molar  and  proper  shaping  of  the  other 
sides,  will  permit  the  removal  and  insertion  of  the  caps  in  the  construc- 
tion, and  ready  adjustment  at  the  cervical  section  when  permanently 
inserted. 

It  is  not  essential  that  the  parallel  lines  of  the  sides  of  prepared 
teeth  or  roots  shall  form  a  right  angle  to  a  straight  hne  between  the 
cervices  of  the  abutment  teeth  or  the  space  between  them.  Teeth  or 
roots  may  slightly  converge  in  the  occlusal  direction,  but  they  must 
not  diverge. 

The  application  of  this  principle  to  the  preparation  of  a  lower  molar 
and  bicuspid  for  an  intervening  bridge  is  shown  in  Fig.  529,  which  is 
typical  of  cases  frequently  presented.  Here  straightening  of  the  pos- 
terior or  distal  side  of  the  bicuspid  and  removal  of  a  portion  of  the  an- 
terior or  mesial  side  of  the  molar,  as  indicated  by  lines,  will  considerably 


Pig.  529. 


Pig.  530. 


aid  in  obtaining  a  form  that  will  permit  of  correct  adjustment  of  the 
caps. 

This  principle  is  further  exemplified  in  Fig.  530,  where  the  inferior 
cuspid  and  the  lateral  incisor  are  used  to  support  a  bridge. 

The  presence  of  decay  on  the  side  of  a  tooth  requiring  the  most 
shaping,  facilitates  the  operation,  as  chisels  and  cross-cut  burs  may  be 
used  to  remove  the  main  portion  of  the  bulging  enamel.  The  cavity 
should  be  excavated  and  filled  with  a  cement,  or  preferably  amalgam, 
previous  to  the  final  shaping. 

Plain  thin  carborundum  disks  will  remove  the  approximal  surface 
towards  the  adjoining  tooth  more  rapidly  than  those  of  vulcarbo,  but 
they  must  be  used  with  greater  precision  to  avoid  their  fracture.  Com- 
mence with  a  disk  of  moderate  circumference  and  follow  with  larger 
sizes.  Removal  or  mutilation  of  the  contour  of  an  adjoining  tooth 
must  be  avoided.  Frequently  the  formation  of  a  space  can  be  advan- 
tageously commenced  with  a  thin  safe-sided  separating  file,  then  in- 
creased with  paper  carborundum-disks.  These  may  be  followed  with 
a  regular  disk.  Small,  moderately  thick  carborundum  wheels  or  disks, 
whose  circumference  has  been  considerably  reduced  by  use,  may  be 


CONSTRUCTION  OF  BRIDGE-WORK 


281 


advantageously  employed  on  the  sides  of  the  teeth  approximal  to  the 
space  to  be  bridged.  The  reduction  of  the  labial  and  lingual  sides  must 
be  such  as  will  give  a  form  that  will  permit  the  edge  of  the  collar  of  the 
crowns  to  slide  over  the  coronal  section,  and  assume  the  proper  position 
under  the  gum  margin.  The  occlusal  surfaces  of  teeth  should  be  re- 
moved sufficiently  to  permit  the  presence  of  an  intervening  surface  of 
metal  capable  of  resisting  attrition.  The  proper  thickness  of  the  metal 
for  this  purpose  is  regulated  by  the  character  of  the  occlusion.  The 
hardness  of  the  metal  to  be  used  for  forming  the  occlusal  surfaces, 
whether  it  is  a  gold  alloyed  with  copper  and  platinum,  or  largely  with 
copper  only,  in  contrast  to  the  gold  plate  used  to  form  the  sides  of  the 
crown,  may  also  be  considered  in  calculating  its  resisting  power. 

The  reduction  of  sound  teeth  to  be  used  as  abutments  in  bridge- 
work  to  an  actual  thimble-shaped  form  is  not  always  necessary,  as 
such  reduction  would  demand  in  many  cases  the  devitalization  of  the 


Fig.  531. 


Fig.  532. 


Fig.  533. 


Fig.  534. 


pulp,  the  vitality  of  which  might  be  preserved  by  the  adoption  of  less 
extreme  trimming.  The  removal  of  contour  and  enough  tooth-struc- 
ture to  parallel  the  sides  so  as  to  permit  the  edge  of  the  collar  of  a  gold 
cap  to  fit  perfectly  at  the  cervical  section,  just  under  the  free  margin 
of  the  gum,  is  sufficient.  To  pass  deeper  than  this  point  will  usually 
demand  considerably  more  reduction  of  the  coronal  section.  Figs. 
53ij  532,  533  and  534  illustrate  upper  and  lower  bicuspids  and  molars 
of  normal  form.  The  lines  indicate  the  amount  of  tooth  substance 
usually  necessary  to  remove  in  such  cases  when  the  pulps  are  vital. 

The  proportion  of  bulging  constituting  the  contour  of  teeth  varies 
considerably.  Short  bicuspids  and  molars  demand  less  shaping  to 
prepare  them  for  the  reception  of  caps  than  longer  teeth.  The  lingual 
sides  of  lower  bicuspids  and  molars  require  much  more  to  be  removed 
than  the  labial.  Second  and  third  molars  free  of  decay  when  the  gingi- 
val margin  covers  the  coronal  section  considerably,  seldom  require 
extensive  shaping. 

In  sound  bicuspids  and  molars  with  the  crown  fully  exposed  and  slight 
recession  of  the  gum;  also  in  teeth  with  small  necks  and  large  contour, 


282 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


a  reduction  of  their  form  sufficient  to  permit  proper  adjustment  of 
the  collar  of  the  metallic  cap  at  the  neck  usually  demands  pulp 
extirpation. 

A  secure  anchorage  to  vital  molars  and  bicuspids,  especially  those  in 
the  mandible,  is  easily  obtained  by  reducing 
the  sides  and  occlusal  surfaces  sufiSciently  to 
allow  the  formation  of  a  cast  or  swaged  cap 
that  will  only  partly  cover  the  coronal  sec- 
tion, and  fit  at  the  margins  of  the  portion 
Pig.  S3S-— a,  A.istheiine  removed,  as  shown  in  Fig.  535.     One,  two 

to    which    the    enamel    is    re-  .  .  i  •        i 

moved,  leaving  a  slight  OT  three  pms  may  be  mser  ed  m  the  cap  for 
shoulder  for  the  edge  of  the  security.     Fig.   536  shows  Dr.  Edward  T. 

Tinker's  method  of  shaping  a  molar  tooth 
for  a  cap  of  this  style.  It  requires  a  greater  removal  of  tooth  struc- 
ture than  that  shown  in  Fig.  535.  MODL  and  MOD  crowns  may 
also  be  utihzed.     (See  Figs.  624,  625,  626  and  627). 

In  a  case  where  a  molar  tips  in  the  manner  shown  in 
Fig.  537,  the  most  advisable  plan  is  to  either  insert  an 
inlay  in  the  occlusal  surface  that  can  be  inserted  in  the 
same  line  as  the  bicuspid  cap;  or  to  crown  the  molar  and 
place  at  the  mesial  side  a  lug  or  attachment  for  the  distal 
end  of  the  bridge.     (See  Part  IV,  Chapters  VI  and  X.) 

The  presence  of  decay  with  extensive  calcification  of 
the  pulp  in  a  tooth  will  admit  of  the  removal  without  pulp 
extirpation  of^more  enamel  and  dentin  than  if  it  were  pef- 
fectly  normal.  1 

When  teeth  are  pulpless,  shaping  always  can  be  more  freely  prac- 
ticed. In  such  cases  the  collar  should  be  carried  well  under  the  gingi- 
val margin  as  a  protection  for  the  devitalized  dentin  against  decay, 


Pig.  536. 


Fig.  537- 

and  the  occlusal  surface  may  be  more  extensively  removed.  Extreme 
reduction  of  the  coronal  section  of  a  tooth  does  not  always  facilitate 
the  work  of  construction,  but  often  the  reverse,  as  straight  or  shghtly 
tapering  sides  and  the  presence  of  a  reasonable  proportion  of  the  crown 
will  steady  the  collar-cap  during  its  formation.     It  will  also  assist  in  its 


CONSTRUCTION  OF  BRIDGE-WORK  283 

retention  in  correct  position  in  the  mouth  for  the  construction  of  the 
bridge-work. 

In  the  preparation  of  the  anterior  teeth  for  post  crowns  with  porce- 
lain facings,  the  canal,  when  necessary,  may  be  reamed  a  little  to  one 
side  at  the  orifice  and  the  post  of  the  crown  correspondingly  tapered  on 
that  side  to  favor  its  insertion  and  removal  from  the  canal. 

As  to  whether  an  incisor  or  cuspid  should  be  entirely  capped  with 
gold,  or  a  method  be  adopted  by  which  the  metal  will  be  only  slightly 
exposed  or  entirely  invisible,  in  preference  to  excising  the  crown  and 
inserting  on  the  root  a  cap  with  porcelain  facing,  is  a  question  to  be 
determined  by  the  conditions  and  circumstances  attending  the  case. 
The  position  and  occlusion  of  a  tooth,  its  shape  and  general  appearance, 
whether  it  is  sound,  free  from  decay,  or  partially  or  extensively 
decayed;  whether  the  pulp  is  living  or  almost  entirely  calcified  or  has  al- 
ready been  devitalized;  also  the  age  and  sex  of  the  patient,  are  condi- 
tions which  should  influence  the  operator  in  the  adoption  of  the  form 
of  construction.  The  illustrations  in  the  succeeding  chapters  on  bridge- 
work  show  numerous  methods  which  may  be  practiced. 

Construction 

The  operative  procedure  as  generally  practiced  in  construction  of 
all  bridge-wojk  is  classified  as  follows: 

First.  Take  two  impressions  and  two  articulating  impressions, 
termed  "bites,"  of  the  case  when  presented  before  operating  on  it, 
and  make  models  and  articulating  models,  one  set  to  use  as  a  study  and 
reference  model,  and  the  other  as  a  preparatory  model  for  outlining 
and  indicating  the  forms  to  which  the  teeth  require  to  be  trimmed.^ 

Second.     Prepare  the  abutment  roots  or  teeth. 

Third.     Make  the  abutment  caps,  crowns  or  attachments. 

Fourth.  Take  a  "bite"  and  impression  with  the  crowns  or  at- 
tachments in  position.  When  a  "bite"  is  taken  separately  or  addition- 
ally to  the  impression,  the  ''bite"  should  always  be  taken  first. 

Fifth.     Make  a  model  and  articulating  model. 

Sixth.  Select  the  porcelain  facings  for  the  dummies  between  the 
abutments  and  grind  and  fit  them  to  position  in  accordance  with  the 
occlusion  of  the  articulating  teeth.  Cover  the  labial  facings  with  a 
plaster  matrix. 

Seventh.  Apply  metallic  backings  to  the  porcelain  facings  and 
additionally,  occlusal  cusps  to  the  bicuspids  and  molars. 

1  A  study  model  is  valuable  to  refer  to  during  the  work  and  especially  so  in 
case  of  subsequent  discussion  over  operations  performed. 


284 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Fig.  538. 


Fig.  539. 


Fig.  540. 


CONSTRUCTION  OF  BRIDGE-WORK 


28s 


Eighth.  Cement  dummy  teeth  and  crowns  together  with  adhesive 
wax  on  model,  remove,  invest  and  join  together  with  solder;  trim  and 
polish. 

The  case  represented  in  Fig.  538  will  be  used  to  illustrate  and  explain 
constructive  details.^  The  abutments  consist  of  the  right  cuspid  root, 
the  crown  of  which  is  to  be  excised,  and  the  first  molar.  The  cuspid 
root  and  molar  crown  having  been  properly  prepared  in  parallel  lines, 
as  shown  in  Fig.  539,  a  gold  collar  crown  with  porcelain  facing  (Rich- 
mond) is  made  for  the  cuspid  and  an  all-gold  crown  constructed  in 
sections  for  the  molar  (Fig.  540). 

Impressions  and  Models. — With  the  crowns  in  position  in  the 
mouth,  an  impression  of  the  case  and  of  the  occluding  teeth  is  taken 


Fig.  541. 

with  plaster  slightly  colored  with  carmine,  to  which  may  be  added,  if 
the  plaster  is  slow-setting,  a  little  potassium  sulfate,  less  in  proportion 
than  salt,  to  cause  it  to  set  quickly.  The  plaster  is  mixed  moderately 
thick  and  either  rolled  in  a  mass  between  the  fingers,  which  should  be 
wet  to  prevent  adhesion  of  the  plaster,  or  with  the  aid  of  a  spoon  it  is 
placed  around  in  the  mouth  on  the  crowns  and  parts  to  be  included  in 
the  bridge,  and  the  antagonizing  teeth  occluded  tightly  and  so  held, 
until  the  plaster  sets  (Fig.  541).  The  mouth  is  then  opened  and  the 
pilaster  carefully  removed.  Should  the  plaster  break,  the  pieces  are 
adjusted  together  and  cemented  with  hard  wax.  The  crowns  are  gen- 
erally removed  in  the  impression;  if  not,  they  should  be  transferred  to 
it  from  the  mouth. 

The  inside  of  the  molar  crown  and  the  cuspid  cap,  also  the  post,  are 
thinly  veneered  with  paraffin. to  obliterate  recesses,  and  later  permit 

*  New  York  State  Board  Bridge. 


286 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


their  removal  from  the  plaster  model.  (See  Part  I,  Chapter  IV.) 
The  entire  impression  is  varnished,  then  oiled  and  a  plaster  model 
first  run  in  the  upper  impression  carrying  the  crowns.  When  the  model 
has  become  well  set,  it  is  mounted  with  plaster  on  an  articulator — an- 
atomical type  preferred — and  the  other  side  of  the  plaster  impres- 


PlG.    542. 

sion,  giving  the  articulation,  is  run  and  the  opposite  section  of  the 
articulator  adjusted.  When  the  impression  plaster  is  removed  (an 
operation  which  is  facilitated  by  its  having  been  colored  with  carmine), 
a  correct  model  and  articulation  of  the  case  will  be  found,  with  the 
crowns  and  caps  in  exact  position  as  they  were  in  the  mouth  (Fig.  542). 


Fig.  543. 


Fig.  544. 


Danger  of  fracture  of  the  form  of  the  occluding  teeth  of  the  articu- 
lating model  or  "bite,"  in  their  removal  from  the  plaster  impression 
may  be  avoided  by  giving  them  the  shapes  illustrated  in  Figs.  543  and 
544.  This  is  done  by  trimming  and  shaping  the  mold  of  the  teeth  in 
the  plaster  impression  at  the  lingual  side  to  form  C  and  C,  and  thor- 
oughly varnishing  and  oiling  before  running  the  plaster. 


CONSTRUCTION  OF  BRIDGE-WORK 


287 


The  shape  given  in  no  respect  impairs  their  form  for  the  articu- 
lating work. 

Selection  and  Adjustment  of  Artificial  Teeth.— In  bridge-work, 
cross-pin  flat-back  plate  teeth,  now  known  as  porcelain  facings  or 
veneers,  are  used  for  incisors  and  cuspids,  and  partial  teeth,  represent- 
ing the  buccal  section  of  the  teeth  and  also  termed  porcelain  facings — 
especially  designed  for  crown  and  bridge- work— are  used  for  bicuspids 
and  molars  (Fig.  545).  Cuspids  are  sometimes  used  to  form  the  facings 
for  bicuspids.  The  facings  in  appearance  should  be  selected  in  accord- 
ance with  the  rules  given  in  "Selection  of  Porcelain  Teeth,"  Part  III, 
Chapter  II.  They  should  be  of  such  a  length  that  when  ground  in 
place,  the  base  at  the  cervix  will  touch  or  rest  on  the  gum,  and  the  occlu- 
sal end  on  the  antagonizing  teeth,  as  shown  in  Fig.  546. 


Pig.  546. 


Fig.  547- 


To  determine  the  proper  position  of  facings  for  producing  the  best 
appearance,  they  can  be  adjusted  in  the  mouth  supported  on  a  narrow 
wax  plate,  with  or  without  the  gold  crown  or  cap  of  the  abutments. 
The  facings  having  been  ground  and  adjusted  to  correct  position  on 
the  model,  plaster  is  placed  on  the  outside  of  the  model,  over  the  labial 
and  buccal  aspects  of  the  facings,  in  sufi&cient  quantity  to  hold  them  in 
position,  thus  forming  a  matrix,  as  seen  in  Fig.  547.  The  wax  is  then 
removed,  exposing  the  lingual  portion  and  permitting  the  forms  and 
position  of  the  teeth  to  be  studied  (Fig.  548).  The  base  of  the  porcelain 
facings  for  the  bicuspid  dummies  can  be  allowed  to  rest  on  the  gum  as 
ground,  or  they  can  be  removed  from  their  investment  and  the  base  of 
each  uniformly  ground  from  the  lingual  side  beyond  the  pins  (A,  Fig. 
549),  straight  to  the  labio-cervical  edge  (B),  so  that  it  only  touches  or 
leaves  a  slight  space.  This  gives  the  form  termed  self-cleansing  space. 
Forming  the  porcelain  facing  with  the  base  resting  on  the  gum,   as 


288 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


indicated  in  Fig.  546,  is  in  the  opinion  of  the  author  preferable,  as  it 
excludes  particles  of  food. 

Another  favorably  considered  method,  as  it  eliminates  the  so-called 
self-cleansing  space  and  offers  a  more  agreeable  surface  to  the  tongue, 
is  to  form  the  dummy  with  a  base  of  slightly  smaller  circumference  than 
the  cervix  of  the  natural  tooth  would  be,  as  shown  in  Figs.  883,  884  and 


^  Pig.  548. 

885,  and  as  used  in  removable  bridge-work.  The  occlusal  edge  of  the 
cuspid  facing  is  shaped  and  protected  with  the  backing,  as  explained  in 
crown- work  (Fig.  301).  To  make  room  for  the  gold  occlusal  cusp  that 
is  to  be  added  to  the  bicuspid  facings,  the  porcelain  is  ground  off  at  an 
angle  of  45°  to  the  line  of  the  hngual  side,  as  shown  at  A,  Fig.  550,  leav- 
ing a  space  at  the  extreme  edge  of  about  one-thirty-second  of  an  inch,  or, 


Fig    549. 


Fig.  550. 


Pig.  SSI. 


if  protection  of  the  porcelain  is  more  to  be  considered  than  appear- 
ance, the  entire  end  can  be  removed  and  restored  with  gold,  as  indicated 
in  Fig.  551.  To  effect  a  uniform  line  of  the  gold  and  porcelain  for  ap- 
pearance, the  angle  for  removal  should  be  the  same  on  all  the  facings 
and  the  line  continuous,  as  shown  in  Figs.  552  and  not  as  in  Fig.  553. 
Backings. — The  bicuspid  porcelain  facings  are  next  backed  as  in 
the  case  of  a  crown.     (See  Part  III,  Chapter  IX.)     The  backings,  if 


CONSTRUCTION  OF  BRIDGE-WORK 


289 


preferred  may  be  extended  down  on  the  curve  of  the  self-cleansing  spaces. 
A  more  desirable  result  is  secured  if  the  backing  extends  only  to  the 
edge  of  the  self-cleansmg  space  and  the  porcelain  is  polished,  as  its 
surface  is  superior  in  cleanliness  to  that  of  gold. 

Occlusal  Cusp-Caps. — Gold  cusp-caps  are  made  in  accordance  with 
the  occlusion  to  form  the  occlusal  portion  as  described  and  illustrated 
in  the  construction  of  gold  crowns,  either  by  swaging  gold  plate  and 


Pig.  552. 


Fig.  553. 


Fig.   554. 


filling  in  the  cusps  with  hard  solder  or  by  casting  (Fig.  554).     (See  Part 
III,  Chapter  VIII.) 

The  matrix  is  next  removed  from  the  surface  of  the  model  by  prying 
it  loose.  The  cuspid  and  molar  crowns  are  warmed,  removed  and  boiled 
in  water  and  soda  to  entirely  remove  the  paraffin  from  inside  the  caps. 
The  outside  metallic  surface  of  each  crown  adjacent  to  the  dummy 
teeth,  is  veneered  with  a  film  of  hard  wax,  by  heating  the  gold  enough 


Fig.  555-  -  ' 

to   melt   the   wax,   when   touched  to  its   surface,  which  causes  it  to 
adhere  with  great  tenacity  to  the  gold. 

An  ensemble  is  next  made  of  the  crowns,  dummy  bicuspids  and  occlu- 
sal cusp-caps  with  the  matrix  on  the  model.  The  different  porcelains 
should  appear  to  touch  on  the  sides  but  should  not  actually  do  so — a 
slight  space  is  necessary  to  allow  for  expansion  and  contraction  of  the 
porcelain  without  checking  when  heated  in  soldering.  Should  any 
touch,  trim  the  side  or  sides  with  a  sandpaper  disk.  The  dummy 
bicuspids  and  occlusal  cusp-caps  and  crowns  are  first  connected  with 
a  small  amount  of  adhesive  wax,  and  when  correctly  adjusted,  rein- 

19 


290 


CROWN',  BRIDGE-,  AND  PORCELAIN-WORK 


forced  with  a  large  quantity  of  hard  wax,  and  are  then  waxed  to  the 
abutment  crowns.  Wax  should  be  placed  in  any  seam  or  place  where 
it  is  desired  to  have  the  solder  flow.  A  trifle  of  wax  is  applied  in  excess 
of  the  amount  of  solder  required,  so  as  to  give  a  slight  surplus  of  solder 
for  finishing.  A  piece  of  iron  wire  about  gage  No.  12  to  15,  bent  on  the 
ends,  as  shown  in  Fig.  555,  maybe  heated  and  inserted  in  the  wax  as  a 
brace.  The  wax  is  chilled,  the  matrix  removed  and  then  the  bridge 
from  the  model,  which  is  then  invested,  as  seen  in  Fig.  556. 


Fig.  556. 

Investing  the  Bridge. — In  investing  a  bridge,  it  is  first  dipped  in 
water,  then  a  httle  investment  material  is  placed  in  each  cap  or  crown 
and  in  every  crevice,  with  a  small  camel's-hair  brush  or  a  chip-blower, 
to  insure  it  against  air  bubbles.  A  little  more  of  the  material  than  is 
sufficient  to  invest  the  bridge  is  next  placed  on  a  sheet  of  paper  and  the 
bridge  is  pressed  into  it,  occlusal  side  up,  and  the  material  brought  over 
in  quantity  a  little  more  than  enough  to  cover  the  occlusal  surfaces, 
but  the  surface  of  the  wax  should  be  left  exposed. 

To  prevent  fracture  of  the  investment  during  the  solder- 
ing process — which  is  liable  to  occur — and  also  to  control  its 
expansion  and  contraction  and  proportionately  a  displace- 
ment of  the  parts  of  the  bridge,  an  iron  wire  about  gage 
No.  15  with  the  ends  twisted  together,  or  a  narrow  strip  of 
sheet  iron  or  nickel  with  the  ends  joined,  may  be  placed  in 
the  investment  to  encircle  it,  about  one-eighth  of  an  inch  from  the 
outer  surface  of  the  bridge,  and  low  enough  on  the  lingual  side  not  to 
obstruct  the  exposure  of  the  parts  to  be  soldered  (Fig.  556.) 

When  the  investment  is  set,  the  wax  is  removed  with  boiling  water 
and  the  investment  trimmed.  If  any  of  the  parts  that  are  to  be  united 
in  the  soldering  do  not  touch  each  other,  the  space  between  them  should 
be  packed  with  gold  foil  or  Corona  gold  to  act  as  a  bridge  for  the  solder. 
Pieces  of  gold  wire  may  be  used  to  aid  in  filling  in  the  right-angle  space 
between  the  occlusal  cusp-caps  and  the  backing  of  the  dummies,  as 
indicated  in  section  in  Fig.  557. 


Fig.  557. 


CONSTRUCTION  OF  BRIDGE-WORK 


291 


Soldering. — ^Thc  case  should  be  heated  slowly.  The  soldering  is 
best  done  on  a  concave  soldering  block  or  a  piece  of  charcoal  with  a 
similar  depression.     (See  "Soldering,"  Part  I,  Chaptei-  VI.) 

Finishing. — After  the  soldering  the  bridge  is  removed  from  the 
investment  and  boiled  in  acid.     The  joints  of  the  backings  and  crowns 


are  trimmed  and  smoothed  with  carborundum  wheels  and  points, 
finishing  burs  and  leather  points  on  the  engine,  also  by  a  cord  drawn 
between  them  (Fig.  65,  Part  I),  and  the  entire  bridge  finely  polished 
with  whiting  or  rouge,  carried  by  a  brush  wheel  on  a  lathe.  Any  little 
pits  that  may  exist  can  be  shaped  with  a  small  bur  and  filled  in  with 


Pig.  559. 

gold  foil  or  Corona  gold.     (See  Part  I,  Chapter  VIII.)     The  bridge  is 

then  ready  for  insertion  (Fig.  558).     If  the  construction  details  have 

been  performed  as  described,  a  finished  piece  of  bridge-work  is  the 

result. 

;•>,  Fig.  559  shows  the  finished  bridge  inserted  in  position.  : 


292 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Variation  in  Method  of  Construction 

Construction  in  Sections. — To  overcome  warping  and  displacement 
of  the  abutment  crown  and  dummy  teeth  from  expansion  and  contrac- 
tion of  the  investment  material  and  gold  solder,  which  occur  especially 
when  large  bridges  are  soldered  in  one  investment,  the  soldering  is  done 
in  sections,  to  be  connected  in  one  or  more  soldering  operations,  as  the 
case  may  suggest.  For  instance,  in  the  finished  typical  case  (Fig.  558) 
the  bicuspid  dummies  could  be  removed  in  position,  invested  and  sol- 
dered together,  trimmed  and  replaced  on  the  model,  cemented  with 
wax  to  the  abutments,  removed,  invested  and  soldered  to  them. 

Soldering  on  the  Model. — Another  method  of  constructing  bridge- 
work  is  to  form  a  model  of  the  case  of  investing  material  and  do  the 
final  soldering  on  the  model.     (See  "Models,"  Part  I,  Chapter  IV.) 


Fig.  560. 

The  abutment  crowns  are  left  in  position  on  the  model.  The  dummies 
are  fitted  between  them  and  cemented  with  wax,  the  matrix  removed, 
the  model  and  bridge  invested  and  soldered  together. 

Correction  of  Warping.^ — When  warping  occurs  to  such  an  extent 
as  to  interfere  with  proper  adjustment,  the  bridge  should  be  sawed  apart 
where  the  displacement  apparently  has  mostly  occurred,  in  the  manner 
least  hkely  to  affect  its  appearance.  The  parts  are  then  cemented 
together  with  hard  wax,  adjusted  in  the  mouth  and  an  impression  taken 
in  an  impression  tray,  using  only  sufiicient  investing  material  to  cover 
the  points  of  the  teeth  and  crowns,  as  shown  in  the  case  of  a  larger 
bridge  in  Fig.  560.  The  bridge  and  the  investing  material  are  then 
removed  from  the  impression  tray  and  more  investing  material  added 
to  complete  the  investment.  The  sections  of  the  bridge  to  be  united 
are  next  exposed  and  soldered  together.     To  permit  the  investing 


CONSTRUCTION  OF  BRIDGE-WORK  293 

material  to  be  easily  removed  from  the  impression  tray,  it  is  well  to 
melt  a  film  of  wax  on  its  interior  surface,  then  cool  and  serrate  the 
surface  of  the  wax.  The  plaster  will  adhere  firmly  to  the  wax  but  will 
loosen  when  the  tray  is  heated. 

Adjustment  and  Insertion. — The  bridge  when  finished  is  adjusted 
in  the  mouth,  every  point  carefully  examined  and  any  alterations  re- 
quired made.  Should  the  edge  of  one  or  more  of  the  abutment  caps 
strike  the  edge  of  the  occlusal  surface  of  an  abutment  tooth  or  the  end 
of  a  root,  so  as  to  interfere  with  the  adjustment  of  the  bridge,  paint 
with  a  paste  of  rouge  and  oil  the  inside  of  that  section  of  the  cap,  dry 
the  surface  of  the  crown  or  root  and  insert  the  bridge  so  that  the  rouge 
on  the  cap  shall  mark  the  interfering  part  of  the  tooth  or  root.  Grind 
off  the  marked  interfering  part,  and  repeat  the  process  if  necessary. 
Should  the  point  of  a  post  strike  the  dentin  to  one  side  of  the  orifice  of  a 
canal  it  is  to  enter,  trim  off  the  point  of  the  post  slightly  on  the  inter- 
fering side  and  if  necessary  also  the  dentin  at  the  edge  of  the  orifice, 
sufficiently  to  permit  the  post  to  glide  to  position.  Painting  with 
rouge,  either  the  post  or  abutment  surface,  as  the  case  suggests, 
accurately  defines  the  interfering  point.  If  -extensive  warping  has 
occurred  in  the  soldering  so  as  to  prevent  correct  adjustment  of  the 
bridge,  it  must  be  remedied  as  described  under  head  of  "Correction  of 
Warping." 

Interfering  points  in  the  occlusion  can  be  determined  either  by  the 
use  of  marking  paper,  or  by  warming  the  surface  of  the  gold,  veneering 
it  with  wax  and  then  occluding  the  teeth.  By  the  latter  method  the 
interfering  point  or  points  are  definitely  marked  in  the  wax. 

When  the  adjustment  of  the  bridge  is  accomplished,  if  desired,  it 
may  at  first  be  temporarily  inserted  for  a  day  or  two,  to  permit  it  to 
settle  into  position  and  define  any  slight  points  in  the  occlusion  that 
may  require  alteration.  If  the  bridge  is  warmed  and  paraffin  to  which 
a  little  aristol  has  been  added  is  placed  in  the  caps  before  inserting,  the 
secretions  will  be  better  excluded  and  a  septic  odor  avoided.  Burnish- 
ing the  collars  will  usually  secure  the  bridge;  if  not,  it  can  be  cemented 
with  a  little  gutta-percha  placed  in  each  cap  instead  of  paraffin.  Should 
there  be  evidence  after  temporary  use  of  the  need  of  changes,  the  re- 
moval of  a  little  of  the  occluding  surface  of  a  crown  or  dummy  at  the 
required  point,  and  of  the  antagonizing  teeth,  will  generally  be  sufficient 
to  correct  it.  For  its  permanent  attachment  the  post  of  the  cuspid 
crown  is  barbed  and  the  cuspid  and  molar  crown  treated  the  same  as 
for  single  crowns,  and  the  bridge  cemented  on  with  oxyphosphate  or 
gutta-percha,  or  a  combination  of  both.  (See  Part  III,  Chapter 
XXIII.) 


294  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Fig.  562. 


Fig.  563. 


CONSTRUCTION  OF  BRIDGE-WORK 


295 


Construction  of  Bridge-Work  Embracing  Both  Sides  of  the  Mouth. 

This  is  exemplified  by  the  case  illustrated  in  Fig.  561.  Retaining  abut- 
ment caps  with  posts  are  made  for  the  two  cuspid  roots,  a  gold  crown  for 
the  right  second  molaF  and  a  gold  inlay  for  the  left  molar  (Fig.  562) .  The 
walls  of  the  inlay  cavity  should  be  inclined  so  as  to  permit  insertion  and 
removal  of  the  inlay  in  an  occlusal  direction.  A  piece  of  iridio-platinum 
wire,  gage  No.  12  or  heavier,  should  be  inserted  in  the  inlay  wax,  with  its 
end  protruding  and  cast  in  the  inlay  to  afford  easy  and  better  attach- 
ment to  the  bridge.  (See  Part  IV,  Chapter  IV.)  Impressions  are 
taken;  the  inner  and  outer  cervical  surface  of  the  caps,  the  gold  crown 


Fig.  564. — Shows  "dummies"  in  various  stages  of  construction  A,  Central 
incisor,  and  B,  bicuspid,  ready  for  m.etallic  backing.  C  is  la  central  backed.  D  D  D, 
porcelain  fronts  as  they  appear  on  insertion  after  the  process  of  backing,  capping, 
and  soldering. 

and  the  cavo-surface  of  the  inlay  are  veneered  with  paraffin  to  later 
permit  their  removal,  and  models  made  and  mounted  on  an  articulator, 
as  shown  in  Fig.  563.  (See  Part  I,  Chapter  IV.)  Porcelain  facings 
are  selected  and  ground  to  position.  The  incisal  edge  of  the  cuspid 
crowns  should  be  ground  and  shaped  so  that  they  can  be  protected  with 
metal  by  extension  of  the  backing,  and  the  incisor,  bicuspid  and  molar 
dummies  treated  in  hke  manner.  The  model  is  then  surrounded  with  a 
matrix  and  the  facings  backed  and  occlusal  cusps  made  for  the  bicuspids 
and  molars,  as  illustrated  in  Fig.  564.  The  two  cuspid  crowns  are 
removed  from  the  model,  invested,  soldered  and  then  readjusted  on  it. 


296 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


The  right  section  of  the  bridge  from  the  second  molar  to  the  cuspid,  and 
the  left  from  the  inlay  to  the  cuspid,  are  cemented  together  with  wax, 
removed,  invested  and  united  with  solder.  The  incisors  are  next 
cemented  together  with  wax,  removed,  invested,  soldered  and  read- 
justed.    The  side  bridges  are  then  readjusted  on  the  model,  the  four 


Pig.  565. 

incisors  cemented  in  position  to  the  cuspids,  with  hard  wax,  and  all 
removed  together,  invested  (Fig.  565),  and  the  three  sections  united 
with  solder.  Fig.  566  shows  the  finished  bridge,  and  Fig.  567  the  bridge 
in  position.     The  inlay  can  be  removed  by  means  of  the  shank  and 


Fig.  566. 

Strongly  united  to  the  bicuspid  dummy.  It  is  often  necessary,  to  over- 
come contraction  and  secure  a  better  relationship  of  the  parts,  ^  to  soldei^ 
together  the  entire  bridge  without  the  inlay  and  then  adjust  and  unite 
the  inlay  to  the  bridge  in  a  final  soldering  operation. 

^  In  some  cases,  the  best  plan  is  to  have  the  patient  wear  the  bridge  for  a  day 
before  attaching  the  inlay,  to  allow  the  bridge  to  settle  to  position. 


CONSTRUCTION  OF  BRIDGE-WORK  297 

A  variation  in  the  inlay  abutment  in  a  case  such  as  this  is  to  use  a 
supporting  instead  of  a  retaining  abutment,  as  shown  in  Fig.  568,  the 
construction  of  which  is  described  in  Part  IV,  Chapter  IV  and  in  Part 
V,  Chapter  I,  Removable  Bridge- Work. 


Pig.  567.  Pig.  568. 

Construction  of  Small  Pieces  of  Bridge -work 

This  is  much  simplified  by  the  following  methods:  Crowns  are  first 
made  for  the  teeth  or  roots  that  form  the  abutments  and  temporarily 
placed  in  position.     The  teeth — dummies — which  form  the  span,  having 


Fig.  569. 

been  ground  and  backed,  preferably  with  the  aid  of  a  model,  are  ad- 
justed and  attached  with  wax  cement  in  proper  position  between  the 
crowns.  The  crowns  and  dummies  are  then  removed  together  in  an 
impression  tray  filled  with  investing  material,  the  inside  surface  of 


298 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


which  has  been  veneered  with  wax  and  the  surface  serrated.  The  im- 
pression tray  is  then  heated  and  the  investment  with  the  crowns  and 
dummies  removed.  More  investing  material  is  mixed  and  the  exposed 
parts  of  the  crowns  and  teeth  covered.  The  investment  when  set  is 
cut  away  sufficiently  to  expose  the  parts  that  are  to  be  filled  in  and 
united  together  in  the  soldering  process.  Figs.  569  and  570  represent 
cases  of  bridge-work  constructed  in  this  manner.     Parts  of  a  larger 


Pig.  570. 

bridge  constructed  in  sections  may  be  similarly  formed  and  then  united. 
In  an  extension  bridge  of  one  tooth  with  the  addition  of  a  supporting 
abutment,  a  method  that  can  often  be  practiced  is;  to  properly  adjust 
crown  and  dummy  tooth  or  teeth  cemented  together  with  wax  in  the 
mouth,  carefully  remove  them  in  position,  invest  and  unite  with  solder. 
The  supporting  lug  can  then  be  added  to  the  dummy,  to  rest  on  or  in  the 
intended  tooth  and  form  the  supporting  abutment. 


CHAPTER  II 

REPLACEABLE  PORCELAIN  FACINGS  AND  TEETH 

REPLACEABLE  ORDINARY  PORCELAIN  FACINGS  WITH  CAST  BOX  BACKING — 
A  PLATE  BOX  BACKING — MANUFACTURED  REPLACEABLE  FACINGS 
AND  TEETH — THE  STEELE — THE  IDEAL — THE  EVSLIN — THE  STEWART 
— THE  DIMELOW — IMPARTIALLY  CONSIDERED 

The  replacement  of  a  fractured  porcelain  facing  that  has  been  at- 
tached by  soldering  to  a  bridge  permanently  cemented  with  oxyphos- 
phate  is  frequently  attended  with  great  difficulty,  and  the  result  is 
often  unsatisfactory  and  doubtful  regarding  permanency. 

Change  of  shade  of  the  porcelain  facing  or  tooth  is  liable  to  occur, 
especially  when  subjected  to  more  than  one  soldering  operation,  when 
accuracy  in  shade  is  a  positive  requirement. 

Fracture  of  porcelain  in  soldering  retards  the  construction  of  the 
work  and  involves  the  labor  of  its  replacement.  a      b         c 

The  desire  to  obviate  such  difficulties  has  caused 

the  introduction  of  various  methods  of  construction, 

in   which    the  porcelain  facings   are  removed   from 

^1,    •  •.•  •  ^  ■,  -,     .  ,  Fig.   571. 

their  position  previous  to  the  soldering  process  and 

afterwards  readjusted  and  cemented  so  as  to  be  easily  replaceable  by 

duplicates  in  case  of  fracture  when  the  work  is  being  worn  in  the  mouth. 

To  simplify  the  application  and  increase  the  use  of  replaceable 
porcelain  facings,  special  forms  are  now  manufactured  and  sold. 

Replaceable  Ordinary  Porcelain  Facings  with  Cast  Box  Backing. 

In  making  a  cap  for  a  crown  to  receive  a  facing  sweat  the  collar  to  the 

floor  or  solder  it  with  the  least  possible  quantity  of  hard  solder;  also  use 

very  Httle  solder  to  connect  the  post.     Select  a  porcelain  facing  with 

long  pins  and  register  the  number  of  mold  and  shade.     This    should 

always  be  done  in  all  styles  of  replaceable  porcelain  facing  work.^ 

Grind,  fit  and  bevel  off  the  incisal  edge  of  the  facing  in  the  usual 

manner  for  a  crown  or  dummy.     Point  the  pins  in  a  cervical  direction 

with  a  slight  curve,  as  shown  at  A,  Fig.  571,  or  incisally,  as  illustrated 

at  B,  if  the  condition  suggests  it,  or  does  not  permit  the  cervical.     If 

the  porcelain  must  be  removed  close  on  both  sides  of  the  pins,  an  up- 

1  To  have  on  hand  a  duplicate  set  ground  and  ready  to  replace  the  worn  one  is 
a  good  plan. 

299 


300 


CROWN-,  BRIDGE;  AND  PORCELAIN-WORK 


right  direction  at  a  right  angle  to  the  surface  of  the  porcelain  with  the 
ends  slightly  hooked  towards  each  other  may  be  preferable,  as  indicated 
at  C. 

When  the  facing  is  ground  and  fitted,  remove,  cleanse  in  boiling 
water,  dry,  oil  the  surface  and  wipe  off  surplus.  If  it  is  the  case  of  a 
crown,  remove  all  the  wax  on  the  cap.  Remount  the  facing  on  the 
cap  and  shape  up  the  lingual  side  with  inlay  or  hard  pink  base-plate 
wax  (A,  Fig.  572).  Chill  wax  and  remove  the  porcelain  facing,  leaving 
the  wax  on  cap  (B).     Insert  graphite  points  in  pin  holes  in  wax  (C), 


insert  sprue  wire,  invest  in  casting  flask  and  cast  in  22-carat  gold. 

When  cast,  adjust  porcelain  facing  to  backing.  Ream  out  with 
a  small  bur  any  obstructions  that  it  may  offer  to  the  proper  insertion 
of  the  pins  and  enough  to  provide  space  for  their  bent  form  (B).  Ce- 
ment facing  to  position  and  retain  under  pressure  for  a  few  minutes  (D). 
If  possible,  avoid  insertion  in  the  mouth  until  the  next  day.  The  same 
method  of  construction  is  applied  to  dummies.  The  backings  can  be 
cast  together  or  separately,  then  joined  with  solder  and  united  to  the 


PM-^-«    -^ 


-PM 


LT 
c    c 

Pig.  573.         Pig.  574.  Pig.  575.     Pig.  576. 


Pig.  577.        Pig.  578. 


abutments  in  the  usual  manner.  It  is  not  advisable  to  cast  backings 
of  abutment  crowns  and  dummies  in  one  piece. 

A  Plate  Box  Backing. — An  easy  method  of  constructing  a  backing 
for  a  replaceable  facing  instead  of  casting,  is  to  slit  the  ordinary  plate 
backing,  and  bend  it  over  the  pins  to  form  the  box  and  then  enclose  the 
sides. 

The  process  is  as  follows:  Place  the  plate  to  be  used  as  a  backing, 
which  may  be  platinum  about  gage  No.  34  to  36,  or  22  to  24-carat 
gold,  gage  No.  36,  over  the  pins  and  extending  one-fourth  of  an  inch 


REPLACEABLE  PORCELAIN  FACINGS  AND  TEETH 


301 


beyond  the  cervical  edge  of  the  base  of  the  pjorcelain,  and  mark  or 
indent  the  metal  with  the  pins,  as  shown  at  the  pin  marks  PM  and  PM, 
Fig.  573.  Slit  the  plate  to  the  pin  marks  on  the  line  of  their  outer  side 
as  indicated  at  C  and  C,  Fig.  574,  and  bend  up  the  piece  of  plate  marked 
L.  Place  the  backing  on  the  facing  in  the  open  space,  and  then  bend 
the  fl:ap  over  and  against  the  pins  close  to  the  porcelain,  as  shown  in  Figs. 
575  and  576.  Clo'fee  the  open  ends  of  the  box  with  two  narrow  strips 
of  the  same  plate  as  the  backing  with  the  pins  in  the  open  space 
bent  as  shown  in  Fig.  577,  and  attach* with  wax,  as  seen  at  B  and  B. 
Remove  the  backing,  paint  the  under  side  of  the  backing  and  box 
with  rouge,  and  invest  with  the  ends  of  the  pieces  of  plate  extended 
into  the  investment.  Solder  with  hard  solder,  pure  or  coin  gold,  as 
the  character  of  the  backing  will  permit.  Trim  ofif  surplus  metal  and 
adjust  porcelain  to  backing,  also  pins  to  box.  If  any  obstruction  to 
pins  exists,  remove  it  with  a  small  bur  and  also  give  the  interior  of 
the  box  a  slightly  countersunk  form.  Fig.  578  shows  the  finished 
backing. 

Manufactured  Replaceable  Facings  and  Teeth 

Manufactured  porcelain  facings  and  teeth  with  metallic  backings 
of  special  forms  aie  preferably  used  by  many. 

The  Steele. — This  form  has  a  round  slot  in  the  center  of  the  porce- 
lain facing  into  which  is  closely  fitted,  and  glides  a  metal  flange,  which 
is  united  to  the  backing,  as  shown  in  Fig.  579. 


Fig.  579. 

For  posterior  teeth,  as  the  manufactured  backing  covers  only  a 
part  of  the  facing,  it  generally  requires  to  be  additionally  extended  over 
the  porcelain,  after  the  facing  is  fitted.  The  backing  is  placed  on  the 
facing,  a  piece  of  pure  gold,  gage  No.  35,  is  burnished  over  the  part  not 
covered  by  the  backing,  large  enough  to  extend  slightly  over  the  sides 
and  edges  of  the  backing  and  porcelain,  as  shown  at  A,  Fig.  580.  This 
extra  plate  is  waxed  to  the  backing,  removed,  invested  and  attached 
with  solder.     It  is  then  burnished  and  swaged  to  accurately  fit. 


302 


CROWN;  BRIDGE-,  AND  PORCELAIN-WORK 


Fig.  581  shows  a  finished  dummy  and  crown  with  Steele  facings. 

The  backings  of  Steele  facings  are  extended  slightly  to  protect 
respectively  the  incisal  and  occlusal  edges  of  the  porcelain.  Fig.  582 
shows  a  Steele  bicuspid  porcelain  tooth  with  a  porcelain  occlusal  section 


Fig.  580. 


Fig.  581. 


Fig.  582 


A  B 


Pig.  584. 


ideal  bridge  with  cuspid  removed 
Fig.   585. 


IDCAt 
POSTERIORAND'READYT 
BACKrNG 


Fig.  586. 


with  another  form  of  backing.     Fig.  583  shows  the  facings  and  tooth 
applied  to  a  bridge. 

The  Ideal. — In  this  style  the  porcelain  facing  is  attached  by  a 
rounded  flange  on  a  manufactured  backing  with  a  pin  on  the  point  of 
the  flange  that  enters  the  facing.     The  flange  fits  into  a  round  slot 


REPLACEABLE  PORCELAIN  FACINGS  AND  TEETH 


.303 


with  an  extension  for  the  pin,  as  shown  in  Fig.  584.  A  shows  the  facing 
in  section,  and  B,  the  backing  viewed  from  the  side.  The  end  of  the 
slot  forms  a  shoulder  to  the  hole  for  the  pin.  The  pin  additionally 
secures  the  flange.  The  position  of  the  pin  in  the  porcelain  is  such  as  to 
leave  the  incisal  edge  of  the  facing  intact.  Fig.  585  shows  a  bridge 
with  Ideal  facings,  the  left  cuspid  removed.  Fig.  586  illustrates  a 
posterior  Ideal  backing  and  tooth. 


Pig.  588. 


Fig.  589. 


The  Evslin. — In  this  form  the  porcelain  facing  is  made  with  a  dove- 
tail socket  to  receive  a  lug  extending  from  the  backing.  Fig.  587  shows 
an  anterior  facing  and  flange,  and  Fig.  588  a  posterior  tooth  with  a 
porcelain  occlusal  section. 

After  the  porcelain  facing  has  been  fitted,  the  gold  or  platinum  back- 
ing is  swaged  to  the  porcelain.  The  end  of  the  flange  that  fits  into  the 
socket  of  the  facing  is  protruded  through  a  perforation  in  the  backing 
and  cemented  with  wax  (Fig.  589).  It  is  then  removed,  invested  and 
soldered  to  the  backing. 


Pig.  590. 


Pig.  591. 


Fig.  592.         Fig.  593.        Fig.  594 


As  the  porcelain  is  tipped  at  an  angle  as  it  is  adjusted  to  the  back- 
ing, it  admits  of  the  incisal  edge  of  anterior  teeth  being  protected, 
as  shown  in  Fig.  590. 

The  Stewart. — This  is  one  of  the  latest  forms  of  replaceable  porce- 
lain facings.  The  facing  is  made  with  two  slots  that  curve  toward  the 
incisal  edge,  into  which  two  flanges  fit,  as  illustrated  in  Fig.  591.  The 
angle  at  which  the  flanges  are  inserted  into  the  backing — which  is 
supplied  by  the  manufacturer — is  such  as  to  permit  protection  of  the 
incisal  edge  by  the  metal.     The  pressure  on  the  porcelain  facing  in 


304  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

mastication  is  in  an  opposite  direction  to  that  in  which  the  flanges  are 
inserted.     In  this  way  the  porcelain  is  made  safe  from  displacement. 

The  Dimelow. — The  principle  in  the  construction  of  this  facing  is 
to  secure  mechanical  ancliprage  by  having  the  pins,  which  are  fastened 
in  the  backing,  slant  in  the  porcelain  from  lingual  to  labial,  incisally. 
The  facing  has  two  holes  placed  in  the  location  to  be  occupied  by  the 
pins,  as  shown  in  section  Fig.  592,  the  backing  in  Fig.  593,  and  the 
facing  backed  in  Fig.  594.  In  the  construction,  the  backing  is  swaged 
to  the  facing.  Holes  are  made  for  the  pins,  which  are  then  adjusted 
in  the  porcelain  through  the  backing,  cemented  with  wax,  backing  and 
pins  removed,  invested  and  united  with  hard  solder.  The  angle  at 
which  the  facing  is  cemented  to  the  backing  permits  protection  of  the 
incisal  edge,  as  is  indicated  in  Fig.  594. 

The  methods  and  forms  of  replaceable  porcelain  facings  presented 
are  the  representative  ones  mostly  now  in  use. 

Impartially  Considered. — Fracture  of  porcelain  facings  is  not  to  be 
seriously  considered,  except  in  unfavorable  occlusions.  In  the  con- 
struction of  the  work  the  percentage  of  such  accidents  is  small, 
and  usually  attributable  to  carelessness  in  soldering  or  lack  of  skill. 
Change  of  shade  in  porcelain  will  occur,  when  heated  several  times, 
but  generally  it  is  only  slightly  apparent. 

In  respect  to  strength  and  liability  to  fracture  in  use,  a  properly 
applied  and  constructed  soldered  porcelain  facing  is  stronger  than  a 
replaceable  one.  If  fracture  of  a  soldered  facing  should  occur,  its 
replacement  on  a  cemented  bridge  is  difficult  and  uncertain  in  result. 
Therefore  in  cemented  bridge-work  where  removal  would  involve  par- 
tial or  entire  destruction,  unless  conditions  of  the  case  permit  of  proper 
and  most  reliable  protection  for  the  porcelain,  the  use  of  replaceable 
porcelain  facings  is  advisable. 

The  cementation  of  facings  to  backings  and  caps  provides  contin- 
uity of  structure  for  the  parts  under  and  around  the  porcelain.  This  is 
not  entirely  secured  in  soldered  facings,  no  matter  how  carefully  con- 
structed. In  the  use  of  one  of  the  best  preparations  of  silicate  cement, 
we  have  an  agent  that  competes  with  zinc  oxyphosphate  for  strength 
and  reliability  for  the  cementation  of  replaceable  facings. 


CHAPTER  III 


FORMS  OF  ATTACHMENTS  FOR  BRmGE-WORK 


SHOULDERS  ON  SUPERIOR  INCISOR  AND  CUSPID  CROWNS  OR  ARTIFICIAL 
TEETH — SOLID  GOLD  DUMMIES — CASTING  METHOD — SECTIONAL 
METHOD — SEAMLESS  CAP  METHOD — ALL-GOLD  HOLLOW  DUMMIES — 
ANCHORAGE  CAVITY  IN  A  SOLID  GOLD  CROWN — ANCHORAGE  CAVITY  IN 
A  GOLD  CAP-CROWN 

Shoulders  on  Superior  Incisor  and  Cuspid  Crowns  or  Artificial 
Teeth. — Shoulders  on  these  teeth  at  the  point  of  occlusion  with  the 
inferior  are  sometimes  desirable,  especially  when  it  is  necessary  to 
open  the  "bite."  To  so  construct,  bevel  the  lingual  side  of  the  incisal 
edge  of  the  porcelain  facing  and  back  with  platinum,  gage  Nos.  38  to  40, 
or  pure  or  platinized  gold  plate,  gage  Nos.  31  to  32, 
allowing  it  to  extend  over  the  incisal  edge  one-thirty- 
second  inch,  as  shown  at  A,  Fig.  595.  To  form  the 
shoulder,  cut  a  piece  of  gold  plate,  bend  and  adjust  it 
to  the  incisal  section  in  accordance  with  the  occlusion, 


Fig.  595. 


Pig.  596. 


Pig.  597. 


Pig.  598. 


as  shown  at  B,  Fig.  596,  and  cement  it  with  wax  to  the  backing,  re- 
move backing,  invest  and  unite  plate  to  backing  with  a  small  quantity 
of  solder,  as  indicated  at  the  point  C,  Fig.  597.  Replace  backing  on 
porcelain  facing,  bend  the  pins,  and  fill  in  the  space  to  the  dotted  line 
D,  Fig.  596,  in  the  soldering  of  the  bridge. 

A  cuspid  crown  may  be  advantageously  used  at  times  to  open  the 
"bite"  to  assist  in  supporting  the  force  of  occlusion  by  giving  it  the  form 
of  a  bicuspid.  The  following  is  descriptive.  Make  cuspid  crown  for 
root  with  beveled  and  protected  incisive  edge,  using  enough  hard  solder 
to  connect  backing  to  cap.  Shape  up  the  lingual  side  with  inlay  wax 
to  a  form  approaching  that  of  a  bicuspid,  remove  the  wax  model  and 
cast  with  pure  gold  (Fig.  598).  When  cast,  wax  to  backing  and  invest. 
20  30s 


3o6 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORIf 


Heat  casting  with  pointed  flame  sufficient  to  melt  the  solder  already  on 
the  backing  and  attach  the  casting,  then  flow  i8-  to  20-carat  solder  over 
the  seam  to  entirely  fill  it  and  insure  a  slight  surplus  for  finishing. 


Solid  Gold  Dummies 

In  a  close  occlusion,  when  the  patient  prefers  strength  to  appearance, 
the  bicuspid  and  molar  dummies  may  be  made  of  solid  gold. 

Casting  Method. — For  one  or  more  dummy  teeth,  moisten  or  slightly 
vaselin  the  surface  of  the  model  and  press  inlay  wax  between  the  abut- 
ments, tightly  occlude  the  articulating  model,  and  get  an  imprint  of  the 
antagonizing  teeth.  Chill  the  wax,  trim  and  carve  it  to  the  desired 
form,  removing  and  placing  it  on  the  model  during  the  operation.  In- 
sert a  sprue  wire,  as  shown  in  Fig.  599,  which  illustrates  a  single  dummy. 

Sectional  Method. — Stamp  a  piece  of  pure  gold  plate,  gage  No.  31, 
to  represent  the  occlusal  surface  (A,  Fig.  600) .  Shape  up  the  form  of  the 
remainder  of  the  dummy  in  wax,  and  over  the  wax  adapt  an  annealed 
piece  of  pure  gold  (B),  gage  No.  32,  to  the  buccal,  mesial  and  distal 
sides,  leaving  the  lingual  open.  Invest  buccal  side  down  and  fill  from 
the  lingual  side  with  scraps  of  20-carat  plate  or  coin  gold. 


Fig.  599 


Seamless  Cap  Method. — Stamp  and  fit  a  seamless  crown  to  the 
space.  SHt  and  lap  the  sides,  if  necessary  to  bring  them  into  form,  and 
then  partly  or  entirely  remove  the  lingual  side.  Fill  the  inside  with 
wax,  invest  and  melt-in  a  lower-fusing  gold  than  the  cap. 

All-Gold  Hollow  Dummies. — All-gold  hollow  dummies  are  recom- 
mended in  a  large  proportion  of  cases  in  preference  to  solid  ones,  es- 
pecially for  lightness.  They  are  formed  as  follows:  Take  a  seamless 
gold  contour  croAvn  of  suitable  size,  articulate  it  to  the  antagonizing 
teeth  and  reinforce  the  interior  of  the  occlusal  surface  with  a  slightly 
lower-fusing  gold  plate.  Cut  away  the  gold  of  the  lingual  section  of 
the  collar  to  the  form  termed  self-cleansing  and  shape  the  neck  of  the 
crown.  Melt  a  small  quantity  of  hard  solder  with  flux  into  the  form  of 
a  globule;  fit  a  piece  of  gold  or  platinum  plate,  about  gage  No.  32, 
over  the  open  side,  flux  the  edge  of  the  gold  crown  and  place  the  ball  of 
solder  on  the  gold  or  platinum,  within  the  gold  cap  (Fig.  601).     Hold 


FORMS  OF  ATTACHMENTS  FOR  BRIDGFl-WORK 


307 


the  cap  in  a  Bunsen  flame  and  heat  slowly  until  the  solder  melts  and 
appears  upon  the  edge  of  the  cap,  then  instantly  remove  from  the  flame, 
trim  the  gold  or  platinum  and  stone  the  edges.  This  gives  a  hermeti- 
cally enclosed  dummy  tooth  of  gold,  from  the  interior  of  which  the  air 
has  been  practically  exhausted  by  the  heat.  The  dummy  can  then  be 
placed  in  its  position  on  the  bridge  and  soldered  in  the  usual  manner. 
Fig.  602  gives  the  lingual  aspect  of  a  bridge,  the  dum- 
mies of  which  were  constructed  in  the  manner  des- 
cribed. The  bicuspid  dummy  is  given  a  self-cleans- 
ing form  and  the  molar  is  shaped  to  rest  on  the  gum. 

Anchorage  Cavity  in  a  Solid  Gold  Crown. — An 
anchorage  cavity  in  a  solid  gold  crown,  to  support 
the  end  of  a  bridge  with  an  inlay  or  bar  (Fig.  603)  is 
constructed    as    follows:   The    natural 
crown  is  ground  down  and  the  cervix 
shaped,  banded,  capped   and  pivoted, 
as   shown  in  Fig.    604.     The   gold  or 
platinum  forming  the  floor  of  the  cap 
on  the  root  is  made  flat  and  left  projecting  a  little  at  the  sides. 

The  form  of  the  remainder  of  the  crown  is  shaped  in  wax  on  the  root- 
cap  and  chilled.  A  cavity  is  then  made  in  the  wax  of  the  form  required 
for  the  slot  or  cavity  to  receive  the  inlay  or  bar.  This  is  best  done  with 
a  fast  revolving  fissure  bur  in  the  engine.     Remove  the  wax  model  from 


Fig.  603. 


Fig.  604. 


Fig.  605. 


Fig.  606. 


the  root-cap,  invest  and  cast.  The  cast  crown  is  then  adjusted  in  proper 
position  on  the  cap.  The  cap  is  filled  with  investing  material  and  the 
gold  crown  wired  or  clamped  to  it,  as  shown  in  Fig.  605,  and  united 
with  solder  to  the  cap,  making  a  perfect  joint. 

Fig.  606  illustrates  from  the  palatal  side  a  bridge  of  two.  solid  gold 
bicuspid  dummies  supported  by  a  bar  anchorage  in  a  solid  gold  crown 
on  the  roots  of  a  molar,  and  an  open-face  crown  on  a  cuspid. 

Anchorage  Cavity  in  a  Gold  Cap-Crown. — A  heavy  seamless  crown 
is  a  very  suitable  form  for  insertion  of  a  socket.     If  a  crown  made  in 


3o8 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


sections  is  used,  the  cusps  should  not  be  reinforced  until  after  the  socket 
has  been  attached.  Cut  out  of  the  side  and  occlusal  surface  of  the 
crown  the  required  space  for  the  socket,  as  shown  at  A,  Fig.  607. 
Fit  a  box  formed  of  two  L-shaped  pieces  of  gold  or  platinum  plate  in 


Pig.  608. 


Fig.  609. 


the  space,  as  seen  at  A  and  B,  Fig.  608,  cement  with  wax,  invest, 
and  solder  from  the  inside,  also  reinforcing  the  cusps.  Fig.  609  shows 
the  finished  socket.  Anchorage  cavity  in  a  cast  occlusal  cusp-crown 
is  described  in  Part  V,  Chapter  V. 


CHAPTER  IV 
ATTACHMENTS  FOR  BRIDGE-WORK  (CONTINUED) 

OPEN-FACE  CROWNS — PREPARATION  OF  THE  TOOTH — TO  FORM  A  DIE — 
SEAMLESS  OPEN-FACE  CROWN  CONSTRUCTION — OPEN-FACE  SEC- 
TIONAL CROWN — CEMENTATION  OF  OPEN-FACE  CROWNS — CAR- 
MICHAEL  ATTACHMENT — THE  STAPLE  ATTACHMENT — MOD  AND  MODL 
OR  TINKER  ATTACHMENTS- — SHAPING — CONSTRUCTION — PLATE  AND 
PIN  ATTACHMENTS — CONSTRUCTION — USE  WITH  PULPLESS  TEETH — 
INLAY  AND  BAR-BRIDGE  ATTACHMENTS — INLAY  ATTACHMENTS — IN- 
CISORS AND  CUSPIDS — CAVITY  FORMATION — ^BICUSPIDS  AND  MOLARS — 
ANOTHER  METHOD — FORMATION — ^BAR  ATTACHMENTS — CONSTRUC- 
TION— CONNECTING  BARS  FOR  BRIDGES — INTERVENING  ROOTS 


Open-face  Crowns 

The  use  of  the  open-face  crown  as  a  bridge  abutment  is  often  ad- 
vantageous and  serviceable,  when  properly  con- 
structed and  applied  in  suitable  cases.  Its  use  is 
mostly  confined  to  superior  cuspids  and  bicuspids 
and  inferior  incisors  and  cuspids.  It  does  not  re- 
quire removal  of  the  pulp. 

Preparation  of  the  Tooth. — Parallel  the  sides 
and  remove  enough  of  the  contour  on  the  cervico- 
lingual  section  to  permit  the  gold  to  fit  at  the  neck. 
Grind  off  enough  of  the  lingual  or  occlusal  surface 
of  a  superior  tooth,  to  allow  a  space  at  least  equal 
to  gage  No.  23  between  it  and  the  antagonizing 
teeth.  Slightly  bevel  the  lingual  side  of  the  incisal 
edge  of  the  inferior  teeth,  to  avoid  showing  gold. 
If  possible,  avoid  removal  of  any  of  the  labial 
surface. 

To  Form  a  Die. — Take  an  impression  in  a  tube 
(A,  Fig.  610)  with  plaster,  and  make  a  fusible 
metal  die  (Part  I,  Chapter  V)  or  take  the  impres- 
sion with  compound  in  a  tube  and  make  an  amalgam  die  (B).     If  an 
amalgam  die  is  formed,   it  is  advisable  to  first  take   a  moldine  im- 
pression of  the  die  in  a  tube  and  run  a  fusible  metal  die  for  the  pre- 

300 


Fig.  610. 


3IO 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Fig.  6ii. 


liminary   shaping  of  the  gold  cap,  reserving  the  amalgam  die  for  the 
final  details. 

Seamless  Open-face  Cap -Crown  Construction. — Select  a  gold  cap 
that  fits  the  neck  of  the  die  closely.  Tap  and  shape  the  cap 
to  the  form  of  the  die.  Remove  the  gold  cap  and  anneal 
it.  Replace  on  die  and  swage  in  a  counter-die.  A  swager 
can  be  used  as"  a  counter-die  (Part  I,  Chapter  V).  Fit 
the  crown  on  the  tooth  and  mark  on  the  gold  the  por- 
tion necessary  to  remove  to  expose  the  labial  surface. 
Make  a  hole  with  a  bur  through  the  gold,  and  with  a  fine  fissure  bur 
cut  out  the  marked  portion  and  finish  with  carborundum  points. 
Reburnish  the  crown  on  both  die  and  tooth.  To  better  resist  the 
strain  of  the  bridge  at  the  cervico-labial  part,  especially 
when  the  strip  is  cut  narrow,  reinforce  it  with  an  addi- 
tional shghtly  narrower  strip  of  the  same  gold  as  the 
crown,  soldered  across  the  surface  and  extended  around 
on  the  sides,  as  shown  in  Fig.  6ii.  The  strip  should  be 
beveled  off  evenly  to  the  surface  of  the  remainder  of  the 
gold. 

Open-face  Sectional  Crown  Method. — Fit  a  gold 
collar  around  the  tooth  long  enough  to  extend  shghtly 
beyond  the  incisal  edge  and  remove  the  gold  at  the  labial 
aspect,  as  shown  at  A,  Fig.  612.  Partly  remove  the 
gold  on  the  lingual  side  and  adapt  the  collar  to  the  sides 
of  the  tooth,  as  seen  at  B.  In  the  vacancy  between  the 
collar  and  tooth  at  the  lingual  side,  fit  and  burnish  a 
piece  of  pure  gold  or,  in  the  case  of  a  very  close  "bite," 
thin  platinum  plate,  which  will  cover  the  exposed  sur- 
face at  that  part  and  fit  in  under  the  edge  of  the  collar. 
C  shows  the  usual  form  of  the  piece  of  plate  before  it 
is  fitted  to  the  collar.     Fill  in  the  space  between  the 

collar  and  piece  of  plate 
with  adhesive  wax;  re- 
move the  collar,  invest 
and  flow  hard  solder  into 
the  space  between  the 
piece  of  plate  and  the 
collar,  remove  the  surplus 
gold  and  trim  level.  D 
and  E  show  a  finished  open-face  crown  with  an  incisal  edge  covered 
and  exposed. 

Another  method  for  the  construction  of  an  open-face  crown  prefer- 


FiG.  613. 


Fig.  614. 


Fig.    612. 


FORMS  OF  ATTACH MRNTS  FOR  BRIDGE-WORK  311 

ably  practiced  by  some  is;  form  a  gold  collar  wide  enough  to  extend  a 
little  beyond  the  incisal  edge,  remove  the  portion  of  the  gold  from  the 
center  of  the  incisal  section,  and  slit  the  palatal  surface  on  both  sides 
of  its  center,  as  represented  in  Figs.  613  and  614.  The  part  at  A  is  bent 
back,  the  edges  of  the  parts  at  BB  are  beveled  and  bent  down  on  the 
tooth  and  burnished  close  to  its  surface.  The  piece  A  is  next  brought 
down  in  position  over  the  parts  BB,  and  adapted  to  the  crown. 


Fig.  615. 

The  collar  has  now  assumed  the  shape  of  a  gold  crown  with  an  open 
face  and  seams  (Fig.  614).  The  seams  are  next  united  by  flowing  solder 
into  each  of  them — a  little  at  a  time — by  holding  the  crown  with 
tweezers  in  a  Bunsen  flame.  The  seams  will  hold  and  retain  solder 
sufficient  to  join  and  fill  them  without  the  solder  flowing  over  the  adja- 
cent parts,  unless  an  excess  of  heat  or  solder  is  applied.  When  the 
soldering  is  completed,  the  crown  is  adjusted,  a  line  showing  the  exact 
portion  of  the  labial  aspect  to  be  exposed  marked  on  the  gold,  the  crown 


removed,  its  edges  trimmed  to  the  mark  and  the  soldered  parts  trimmed 
level. 

Fig.  615  illustrates  a  bridge  in  which  the  inierior  incisors  are  sup- 
ported by  open-face  crowns  on  the  cuspids.  Fig.  616  represents  the 
restoration  of  the  inferior  bicuspids  and  a  molar  on  the  right  side  by  a 
bridge  with  an  open-face  crown  on  the  cuspid  and  an  all-gold  crown  on 
the  molar. 

The  Cementation  of  Open-Face  Crowns. — To  secure  a  better  adhe- 
sion of  the  cement  in  the  cementation  of  such  crowns,  the  surface  of 
the  enamel  .should  be  cleaned  with  pulverized  pumice,  wet  with  aromatic 


312 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


sulfuric  acid.  The  tooth  is  washed  and  dried  perfectly.  The  cement 
should  be  thoroughly  mixed  to  the  consistence  of  a  thick  cream,  the 
inside  of  the  crown  and  band  covered  with  it,  then  the  surface  of  the 
tooth — especially  the  cervico-labial  section — and  the  bridge  brought  to 
position. 

When  the  strip  of  gold  which  traverses  the  cervico-labial  section  is 
made  narrow,  the  liability  of  the  cement  to  wash  out  at  that  part  in 
time  is  one  of  the  difficulties  connected  with  the  use  of  this  form  of  crown. 

Fig.  617  shows  forms  of  cap  crowns  for  bicuspids.  When  the  gold 
is  removed  at  the  cervico-buccal  part,  the  crown  can  be  additionally 
secured  by  a  pin  introduced  and  soldered,  as  shown  at  A,  also  in  Fig. 
618,  supporting  a  dummy.  A  more  secure  form  is  to  cut  two  grooves, 
as  shown  in  Fig.  619,  on  the  mesial  and  distal  sides  of  the  natural  tooth, 
for  the  reception  of  two  iridio-platinum  pins  passed 
through  and  soldered  to  the  occlusal  surface.  If  a 
line  of  wax  is  placed  between  the  pins  and  the  cap 
on  the  inner  surface  before  investing,  the  solder  may 


Pig.  617. 


Fig.  618. 


Fig.  619. 


be  partly  drawn  in  between  each  pin  and  the  gold  of  the  cap,  to  better 
secure  the  pins,  by  directing  a  large  flame  under  the  investment. 

In  most  cases  where  open-face  crowns  are  used  on  the  upper  teeth, 
the  gold  forming  the  distal  side  of  the  cap  can  be  brought  around  slightly 
on  the  labial  surface  of  the  tooth,  without  being  observable  when  viewed 
from  the  front;  but  it  must  be  cut  short  at  the  mesial  side,  and  not 
allowed  to  extend  beyond  the  line  of  the  porcelain  facing  placed  beside 
it,  as  seen  in  Fig.  618  and  619.  On  the  inferior  teeth  the  band  of  gold 
which  extends  across  the  cervico-labial  aspect  needs  to  be  removed 
only  enough  to  avoid  exposure  in  speaking.  Consequently  much  more 
gold  may  be  left  at  that  section  on  inferior  than  on  superior  teeth. 

The  cast  Carmichael  or  MODL  Attachment  is  a  good  form  to 
apply  in  many  cases,  such  as  seen  in  Figs.  618  and  619. 

The  Carmichael^  Attachment. — This  consists  of  a  gold  cap  that 
covers  the  prepared  natural  crown  on  the  lingual,  occlusal  and  approxi- 

1  Dr.  J.  P.  Carmichael. 


FORMS  OF  ATTACHMENTS  FOR  BRIDGE-WORK 


313 


Fig.  620. 


A,  Groove  in  tooth 

B,  Cap. 
a.  Cap  in  po?itioD. 

Pig.     621. 


Pig.  622. 


Pig.  623. 


314 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


mal  sides.  It  is  retained  by  a  groove  which  runs  across  the  occlusal 
surface  and  at  right  angles  along  the  approximal  sides  towards  the 
gum-margin  (Fig.  620).  Its  use  is  largely  restricted  to  cuspids  and 
bicuspids.  As  originally  constructed,  a  thin  platinum  or  gold  cap  was 
first  shaped  to  the  form  of  the  prepared  section  of  the  tooth  and  then 
reinforced  with  small  pieces  of  clasp  gold,  united  with  solder.  Fig.  621 
shows  such  a  crown  off  and  in  position  on  a  tooth,  and  Fig.  622  a 
case  of  bridge-work  constructed  with  these  attachments.  Fig.  623 
shows  Dr.  Carmichael's  device  for  gaging  the  lines  of  the  grooves  and 
sides  of  the  teeth  that  are  capped. 

The  Staple  Attachment. — The  Staple  attachment  differs  from  the 
Carmichael  in  that  a  wire  staple  is  placed  in  the  groove  instead  of 
burnishing  the  matrix  into  it  and  flowing  in  solder. 


MOD  and  MODL  or  Tinker^  Attachments 

The  Carmichael  and  Staple  attachments  are  being  superseded  by 
similar  improved  cast  forms  termed  MOD  and  MODL  attachments  and 
crowns.     The  first  mentioned  covers  only  the  mesial,  occlusal  and  distal 


Fig.  624. 


Fig.  625. 


Fig.  626. 


surfaces  and  the  latter  the  mesial,  occlusal,  distal  arid  lingual.  The 
caps  are  extended  to  within  about  one-sixteenth  inch  of  the  gum  margin, 
requiring  only  a  moderate  removal  of  tooth  structure;  this,  as  the  caps 
are  intended  for  use  on  teeth  with  vital  pulps,  makes  this  method  com- 
paratively preferable  to  others  requiring  a  more  extensive  removal. 

Shaping. — For  an  MOD  crown  the  tooth  generally  is  best  first 
trimmed  on  the  approximal  sides  with  a  slight  slant  to  the  line  of  the 
cervical  third  (AA,  Fig.  624).  The  occlusal  surface  is  next  uniformly  re- 
moved one-thirty-second  inch  or  more  as  conditions  suggest,  forming  a 
depression  (B,  Fig.  625).  This  removal  is  next  extended  to  and  on  the 
approximal  sides,  forming  a  small  ledge.  Occluding  the  teeth  on  a 
piece  of  wax,  then  holding  the  wax  up  to  the  light,  will  show  any  point 
requiring  additional  trimming  at  the  occlusal  or  anchorage  surface. 

For  the  MODL  crown  the  enamel  of  the  lingual  side  is  uniformly 
additionally  removed  to  within  about  one-sixteenth  inch  of  the  gum, 

1  Dr.  Edward  T.  Tinker. 


FORMS  OF  ATTACHMENTS  FOR  BRIDGE-WORK 


315 


to  the  line  of  the  removal  of  the  mesial  and  distal  section,  forming  a 
small  shoulder,  as  shown  at  C,  Fig.  626.  Two  slight  parallel  grooves 
are  made  on  each  side  of  the  tooth  at  the  part  G,  to  secure  retention  of 
the  cap.  The  line  of  these  grooves  must  permit  removal  in  an  occlusal 
direction,  also  be  parallel  with  the  line  of  any  other  crown  or  attach- 
ment present.  In  trimming  use  a  small  disk  in  cutting  across  the  incisal 
or  occlusal  surface.  The  cut  should  not  be  made  so  close  to  an  incisal 
edge  as  to  weaken  it.  In  bicuspids  and  molars  the  same  precaution 
should  be  taken  not  to  weaken  the  cusps  in  shap- 
ing, or  if  necessary  they  may  be  reduced  and  entirely 
covered  with  the  cap.  Fissure  burs  aid  in  forming 
the  grooves. 

Construction. — The  wax  model  is  made  by  form- 
ing a  wax  cap  over  and  around  the  tooth  the  shape 
of  the  required  crown  by  either  the  direct  or  indirect 
method,  or  preferably  the  combined  use  of  both.  The 
form  of  the  occlusal  surface  is  defined  by  occluding  the  teeth.  The 
sides  of  the  wax  cap  are  trimmed  and  shaped  to  make  a  flush  joint  with 
the  cervical  ledge  (C,  Fig.  626),  and  the  wax  on  the  labial  or  buccal 
surface  entirely  removed.  The  sprue  wire  is  inserted  as  shown  in  Fig. 
627,  and  the  wax  cap  removed,  invested  and  cast.  An  alloy  formed  of 
two  parts  22-caratgold  plate  and  one  part  clasp  gold  is  recommended  for 
these  caps.^     It  contains  about  four  per  cent,  platinum. 


Fig.  627. 


Fig.  628. 


Fig.  629. 


Fig.  628  shows  an  MODL  crown  utilized  to  support  a  first  bicuspid 
dummy  with  a  lug  to  rest  on  the  cuspid. 

Plate  and  Pin  Attachment.— This  form  of  attachment  when  apphed 
to  a  tooth  with  a  vital  pulp  is  mostly  used  to  support  a  lost  adjoining 
tooth,  or  to  assist  in  supporting  the  end  of  a  bridge  in  connection  with 
other  abutments. 

Fig.  629  will  be  used  as  a  typical  case  to  explain  the  method.  Re- 
move enough  of  the  lingual  side  of  the  cuspid  and,  if  necessary,  the  in- 

1  Formula  of  Dr.  E.  T.  Tinker. 


3i6 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


cisal  edge  of  the  lower  tooth,  to  leave  a  space  equal  at  least  to  gage  No. 
22.'  The  trimming  is  best  done  with  small  wheels  or  points,  so  that  the 
part  assumes  the  shape  of  a  depression  with  a  defined  ledge  forming  the 
margin,  as  shown  at  L,  Figs.  629  and  630.  Three  holes,  size  of  gage 
No.  20,  are  next  drilled  on  the  palatal  side,  one  each  being  placed  at 
the  approximal  sides  and  towards  the  cervico-lingual  section.  These 
holes  are  drilled  in  a  direct  line  with  the  axis  of  the  tooth,  as  indicated 
in  Fig.  630.  The  holes  at  the  approximal  sides  are  to  occupy  that  por- 
tion of  the  tooth  structure  which  is  generally  included  in  approximal  de- 
cay that  does  not  expose  the  pulp.  If  a  gold  filling  or  inlay  occupies 
that  portion,  it  should  be  drilled  into  the  same  as  though  it  were 
the  tooth.  If  the  filling  or  inlay  is  a  substantial  one,  it  will  not  be 
disturbed. 

Construction. — Take  an  impression  in  compound  of  the  lingual  side 
of  the  tooth,  make  an  amalgam  die  and  mount  in  a  swager.     Swage 


Fig.  630. 


Pig.  632. 


Fig.  633. 


and  adapt  to  the  lingual  surface,  extending  onto  the  approximal  side 
where  the  artificial  tooth  is  to  be  adjusted,  a  piece  of  thin  platinum  about 
gage  No.  38.  This  little  plate  of  metal  is  fitted  to  the  surface  of  the 
tooth  and  perforated  over  the  holes.  Three  iridio-platinum  pins,  gage 
No.  20,  which  have  been  roughened  by  rolling  under  a  file,  are  next 
inserted  in  the  holes,  attached  to  the  plate  with  wax,  the  whole  removed, 
invested  and  soldered  with  pure  gold.  Only  one  pin  may  first  be  in- 
serted and  soldered  and  then  the  others  added.  Fig.  63 1  shows  the  cavo- 
surface  side  of  the  plate.  The  plate  is  next  refitted,  edges  trimmed, 
removed,  invested  and  reinforced  with  a  veneer  of  pure  gold.  It  is 
then  fitted,  invested  and  reinforced  with  coin  gold.  The  artificial 
tooth  is  attached  to  the  plate  and  a  lug  added,  resting  on  the  central 
incisor,  as  shown  in  Fig.  632. 

The  line  of  the  pins  in  the  tooth  structure  being  close  to  that  of  the 
line  of  force  exerted  in  mastication  prevents  displacement  and  better 
permits  insertion  and  removal  of  the  attachment  during  the  construction. 


FORMS  OF  ATTACHMENTS  FOR  BRIDGE-WORK 


317 


As  a  support  for  teeth  loosened  by  pyorrhea,  this  pin  cap  attach- 
ment, in  some  cases,  may  be  used  without  removal  of  the  pulp.  On 
account  of  the  narrowness  of  the  lower  incisors,  its  application  is 
confined  to  the  cuspids. 

Use  with  Pulpless  Teeth. — In  pulpless  teeth  only  one  pin  extended 
into  the  pulp-canal  is  necessary,  as  illustrated  in  Fig.  633.  Small  or 
narrow  teeth  require  the  removal  of  the  pulp  and  the  use  of  a  single  pin. 

Inlay  and  Bar-Bridge  Attachments 

Attachments  of  this  style  are  employed  to  anchor  the  ends  of  a 
bridge  in  the  coronal  section  of  natural  teeth  used  as  abutments.  Fail- 
ure to  appreciate  the  limitations  of  this  device  and  faulty  construction 
are  responsible  for  disappointments  in  its  use.  Its  employment  should 
be  confined  to  pulpless  teeth,  or  to  teeth  where  extensive  calcification 
of  the  pulp  exists,  to  permit  a  deep  and  secure  anchorage  of  the  inlay 
or  bar.  When  one  end  of  the  bridge  is  retained  by  a  crown,  the  other 
end  may  be  retained  by  an  inlay  or  bar.  In  the  case  of  pulpless  teeth, 
an  inlay  or  bar  in  certain  cases  may  be  used  on  each  end  of  a  bridge  of 
one  or  two  teeth,  and  occasionally  three  teeth,  but  not  reliably  on  more. 


Inlay  Attachments 

Incisors  and  Cuspids. — This  form  of  attachment  is  seldom  used 
except  in  pulpless  incisors,  or  where  extensive  calcification  is  present, 
owing  to  the  difficulty  of  obtaining  suf- 
ficient depth  for  an  anchorage  inlay  when 
the  pulp  is  present.     The  Pin  and  Plate,        |  i!iaa;i/        /;JM  1\ 


Fig.  634. 


Fig.  635. 


and  Carmichael  attachments  offer  preferable  forms  of  support.  In  the 
case  of  cuspids,  the  use  of  an  inlay  is  more  frequent,  as  their  form  is 
more  favorable. 

Cavity  Formation. — In  an  incisor  or  cuspid  with  a  vital  pulp  the 
anchorage  cavity  is  formed  in  the  Ungual  portion  of  the  tooth,  extend- 
ing from  the  approximal  surface  next  to  the  space  to  be  bridged,  two- 
thirds  to  three-fourths  or  entirely  across  to  the  other  approximal  side. 


3i8 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


The  cavity  should  be  given  a  retentive  form  with  a  flat  base  and 
with  sides  cut  straight  or  diverging  only  very  slightly  from  a  right  angle 
to  the  orifice,  as  shown  in  Fig.  634.  One  or  two  pins  may  also  be  in- 
serted. When  the  cavity  is  to  constitute  one  of  the  supports  of  a  bridge 
with  a  crown  that,  can  only  be  adjusted  in  an  occlusal  direction,  the 
cavity  should  be  shaped  so  that  the  inlay  can  also  be  inserted  in  the 
same  direction.  In  a  pulpless  tooth  a  smaller  sized  inlay  can  be  used 
and  anchored  in  the  root-canal  with  a  post,  as  shown  in  Fig.  635.  Thus 
anchored  an  inlay  furnishes  a  most  reliable  sup- 
port. The  post  or  pins  should  be  paralleled  to 
the  other  abutments  the  same  as  the  inlays  are, 
to  permit  insertion  in  an  occlusal  direction. 

Bicuspids  and  Molars. — ^For  these  teeth 
various  shaped  inlays  are  used  as  a  retentive 
abutment.  The  approximo-occlusal  and  the 
occlusal  are  the  forms  generally  applied.  To  both  these  forms,  espe- 
cially the  occlusal  in  cases  with  vital  pulps,  one  to  four  small  pins  should 
be  inserted  for  the  reason  that  an  inlay  used  as  a  retentive  abutment 
must  withstand  a  stress  not  required  in  a  merely  restorative  operation. 
When  the  tooth  is  pulpless  one  inserted  pin  of  proper  size  is  sufficient. 
In  teeth  with  vital  pulps,  the  anchorage  cavity  should  be  extended 
well  across  the  occlusal  surface,  as  shown  in  Fig.  636  (a  bicuspid),  and 


Pig.  636. 


Fig.  637. 


[Fig.  638. 


Pig.  639. 


Fig.  637  (a  molar).  The  cavity  should  be  cut  as  deep  as  the  presence 
of  the  pulp  will  properly  permit.  Pins  may  be  inserted  at  points  that 
will  give  stability  and  not  impinge  on  the  pulp,  as  shown  at  A,  Fig. 
636,  also  in  Fig.  637  and  Fig.  638  in  section.  In  an  anchorage  inlay  of 
the  form  shown  in  Fig.  639  pins  inserted  at  the  pomts  C,  D  and  E, 
will  maintain  it  securely  in  position.  In  pulpless  teeth  the  inlay  cavity 
can  be  made  smaller,  as  a  large  post  can  be  used  to  anchor  it. 

Pins  are  best  made  of  iridio-platinum  wire,  gage  Nos.  19  to  21,  which 
has  been  rolled  under  a  file.  To  secure  adhesion  of  the  pin  to  the  gold 
in  the  casting,  veneer  the  portion  of  the  end  to  be  extended  into  the 


FORMS  OF  ATTACHMENTS  FOR  BRIDGE-WORK  319 

inlay  wax  with  a  film  of  pure  gold.  This  is  easily  done  by  perforating 
a  pellet  of  gold  foil  with  the  end  of  the  wire  and  holding  it  in  a  Bunsen 
flame. 

The  pin  is  heated  and  the  shank  veneered  with  adhesive  wax  to 
insure  adhesion  of  the  inlay  wax.  The  pin  is  placed  in  the  warmed 
inlay  wax,  inserted  in  the  hole  in  the  dentin  and  the  wax  pressed  into 
the  cavity  and  shaped  as  required.  It  is  then  chill#d,  removed,  in- 
vested and  cast  with  the  pin. 

Another  Method.— When  the  inlay  model  is  formed  as  above 
described,  slightly  warm  and  remove  the  pin  or  pins,  by  first  placing  a 
hot  instrument  against  the  end  to  loosen  them,  then  chill  the  wax  and 
remove  the  inlay  model.  In  the  place  of  each  pin  insert  a  carbon  of 
the  same  gage  slightly  roughened  to  catch  in  the  wax  and  with  the 
extended  end  long  enough  to  engage  in  the  investment. 

When  the  inlay  has  been  cast  and  fitted  to  the  cavity,  the  pin  is 
adjusted  to  position,  the  hole  in  the  gold  being  enlarged  if  necessary 
attached  with  wax,  the  inlay  removed,  invested  and 
the  pin  united  with  solder,  using  the  smallest  pos- 
sible quantity;  or  the  inlay  may  be  cemented,  the 
pin  then  introduced  and  cemented  in  the  hole  and 
inlay,  the  excess  of  the  pin  cut  off,  the  end  trimmed 
level  and  the  end  of  the  pin  and  inlay  burnished 
and  polished. 

This  latter  method  is  advantageous  when  it  is  ^^^'  ^'^°' 

desirable  to  have  a  pin  or  pins  at  a  tangent  to  avoid  impingement 
on  the  pulp,  in  a  case  of  bridge-work  where  the  pins  in  two  inlays  re- 
quire to  be  pointed  in  opposite  directions,  as  shown  in  Fig.  640. 

Formation. — This  is  usually  done  by  the  cast  gold  inlay  method. 
(See  Part  III,  Chapter  XVII.)  When  pins  are  to  be  inserted  in  the  ca- 
vity of  an  incisor  or  cuspid,  the  matrix  method  is  often  preferable,  to 
permit  adjustment  of  the  pins  by  soldering  them  in  position  ui  the 
matrix  with  pure  gold  to  secure  accuracy  of  position  in  the  finished 
inlay.  The  inlay  can  be  finished  either  by  investing  the  matrix  and 
flowing  in  pure  or  22-carat  plate,  or  it  can  be  shaped  with  wax  and 
completed  by  the  casting  method.  (See  matrix  gold  inlays,  pages 
219,  233  and  248.) 

The  inlay  attachment  is  especially  applicable  to  cases  of  teeth 
which  tip  mesially,  where  the  use  of  an  inlay  as  an  abutment  frequently 
simplifies  construction  and  permits  formation  of  a  better  occlusion,  as 
shown  in  Fig.  641. 

Bar  Attachments. — This  form  of  attachment,  though  seldom  used 
since  the  advent  of  the  cast  inlay,  is  often  a  preferable  method  for  the 


320 


CROWN;  BRIDGE-,  AND  PORCELAIN-WORK 


posterior  teeth  when  conditions  favor  its  apphcation.  A  bar  requires 
less  removal  of  the  occlusal  surface  to  properly  secure  it,  and  is  more 
easily  removed  from  the  cavity  without  mutilation  than  an  inlay,  when 
circumstances  require  it.  For  stability,  as  compared  to  an  inlay,  it  is 
fully  equal  to  the  requirements  when  properly  formed  and  inserted. 

Construction. — Enough  tooth  structure  is  removed  to  place  the  bar, 
as  shown  in  section  in  Fig.  642.  Fig.  643  illustrates  the  mesial  side, 
showing  the  dovetail  form  of  cavity.  The  wire  forming  the  bar  is 
given  the  shape  illustrated  and  about  the  width  of  the  orifice  of  the 
cavity.  The  bar  is  made  of  heavy  iridio-platinum  wire,  or  it  may  be 
formed  of  three  wires,  gage  No.  20,  arranged  in  triangular  form,  as  seen 
in  Fig.  643,  the  wires  being  soldered  together  with  pure  gold.     This 


Fig.  641. 


Fig.  643. 


Fig.  644. 


triangular  shaped  bar,  when  fastened  with  filling  materials  in  the  dove- 
tail cavity  in  the  tooth,  with  the  right-angled  point  on  its  end  addition- 
ally anchored  in  the  distal  hole,  is  secured  in  a  manner  that  can  be 
relied  upon. 

The  bar  is  fixed  in  the  cavity  and  slot  with  amalgam,  and  its  position 
is  secured  against  disturbance  while  the  amalgam  is  setting,  by  a  few 
pellets  of  gold  foil  condensed  in  two  or  three  pits  drilled  in  the  tooth 
structure  on  each  side  of  the  bar,  just  before  the  amalgam  is  placed  at 
those  points,  as  shown  in  Fig.  644.  The  amalgam  should  be  used  soft, 
so  that  the  bar  can  be  imbedded  in  it.  The  surplus  mercury  is  then 
worked  out  by  compression  with  pellets  of  cotton.  The  triangular 
shape  of  the  cavity  and  of  the  bar  permits  the  amalgam  to  lock  the  bar 
securely. 


CHAPTER  V 


BRIDGE  CONSTRUCTION  ON  VITAL  TOOIH  ABUTMENTS  AND  PIERS 

Recent  scientific  investigation  of  the  subject  of  focal  infection 
caused  by  pulpless  teeth,  and  the  serious  pathological  conditions  in 
many  cases  traced  as  directly  attributable  thereto,  has  demonstrated 
to  the  dental  profession  the  importance  of  pulp  conservation  in  all 
classes  of  operations. 

In  the  preparation  of  vital  teeth  as  supports  for  bridge-work  many 
methods  require  an  extensive  removal  of  the  enamel  and  of  the  dentin. 
Proportionate  to  the  area  of  enamel  removed,  and  more  especially  of 
dentin,  is  calcification  of  the  pulp  induced.     Calcification  of  the  pulp 


Fig.  645. 

lessens  it  in  size  and  impairs  its  function  more  or  less.  Extensive 
progressive  calcification  frequently  results  in  complete  calcification  and 
obliteration  of  the  pulp.  Consequently,  those  forms  of  attachments 
suitable  for  use  in  fixed  or  removable  bridge-work  that  require  the  least 
alteration  or  mutilation  of  the  coronal  section  of  a  vital  tooth  are  the 
most  favorably  considered. 

For  retentive  attachment  in  fixed  bridge-work  various  methods  can 
be  practiced  that  do  not  necessitate  pulp  extirpation.  Of  this  class  as 
here  mentioned  or  described,  those  demanding  the  removal  of  the 
smallest  quantity  of  tooth  structure  will  be  enumerated  first. 

All-gold  cap-crowns  for  short  teeth  made  seamless  or  in  sections, 
cuspids  and  such  as  have  but  slight  contour  stamped  on  a  die  cast 
from  a  mold  of  the  teeth. 


21 


321 


322  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Open-face  all-gold  cap-crowns  (Figs.  6 lo  to  615). 

Plate  and  pin  attachment  (Figs.  629  to  632). 

Inlay  and  bar  attachments  (Figs.  634  and  636  to  644). 

Carmichael  and  MODL  crown  attachments  (Figs.  620  to  628). 

The  typical  case  described  in  Fig.  538/  is  here  shown  (Fig.  645) 
constructed  with  a  partial  crown  (Carmichael)  on  the  cuspid  and  a  cast 
partial  cap-crown  on  the  molar. 

The  attachments  are  made,  placed  in  position  on  the  abutments 
and  an  impression  and  bite  taken  with  plaster  that  will  remove  the 
attachments  in  position.  A  model  and  articulating  model  are  then 
run  and  mounted  on  an  articulator  and  the  remainder  of  the  construc- 
tion conducted  as  described  in  Part  IV,  Chapter  I,  Figs.  542  to  558. 

All-gold  cap  and  open-face  crowns,  also  inlay  and  bar  attachments 
that  likewise  permit  pulp  conservation,  as  has  been  described,  may  be 
used  as  conditions  suggest. 

1  State  Board  bridge  model. 


CHAPTER  VI 

PORCELAIN  CROWN  (d.ETACHED-POSt)  BRIDGE-WORK — CAST  SANITARY 
BRIDGE — ^SANITARY  PORCELAIN  AND  GOLD  BRIDGE — EXTENSION 
BRIDGES — MECHANICAL  PRINCIPLES  GOVERNING  CONSTRUCTION — 
A  LUG  SUPPORT — LUG  ANCHOR  WITH  LOCK-PIN 

Porcelain  Crown  (Detached-post)  Bridge-work. — The  construc- 
tion of  bridge-work  with  a  display  of  gold  visible  when  the  patient  is 
talking  or  laughing,  in  very  objectionable  to  many  for  esthetic  reasons 
and  the  necessity  for  it  frequently  questioned  by  patients. 

The  objectionable  displiay  of  gold  in  these  cases  is  mostly  located  at 
the  buccal  cusps  of  the  upper  bicuspids,  the  incisal  tips  of  the  anterior 
lower  teeth,  and  the  occlusal  surfaces  of  the  lower  bicuspids  and  molars. 

These  objectionable  features  prompted  the  application  of  detached- 
post  crown  teeth  to  such  cases,  and  the  manufacture  of  special  forms 
of  teeth.  Besides  their  cosmetic  effect,  other  advantages  are  claimed 
for  their  use,  viz.  (a)  As  the  porcelain  is  removed  from  the  work  in 
soldering  operations,  the  risk  of  fracture  and  change  of  shade  is 
eliminated,     (b)  They  are  replaceable  in  case  of  fracture  in  use,^ 

In  the  use  of  detached-post  crowns  as  dummies  for  bridges,  the 
backings  or  supports  which  are  joined  together  to  form  the  bridge  must 
either  rest  directly  on  the  gum  or  leave  only  a  shallow  V-shaped  space 
which  cannot  be  termed  self-cleansing  as  well  as  that  which  is  made 
with  the  ordinary  porcelain  facings. 

The  S.  S.  White,  Davis,  Ash's  detached-post  crowns,  the  Goslee 
tooth  with  a  specially  designed  base,  and  diatoric  teeth  are  mostly  used 
in  this  style  of  work.  Detached-post  crowns  and  diatoric  teeth, 
when  used  for  abutment  crowns,  are  ground,  fitted  and  backed  as 
described  in  "Detached-post  Collar  Crowns,"  (Part  III,  Chapter 
XVI)  with  the  addition  that  on  the  sides  of  the  crowns  approximal  to 
the  bridge  a  slot  is  ground,  into  which  the  hacking  on  the  base  and 
lingual  side  is  extended  and  burnished. 

This  side  flange  to  the  backing  should  be  reinforced  with  hard  solder 
or,  when  a  cast  backing  is  used,  the  flange  should  be  made  proportion- 
ately strong,  as  shown  in  Fig.  646,  which  illu;strates  a  porcelain  cuspid 

^  In  the  use  of  all  forms  of  replaceable  teeth,  the  number  and  shade  should  be 
recorded  with  the  name  of  the  patient,  as  it  simplifies  the  procuring  of  an  exact 
duplicate. 

323 


324 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


crown  ground  and  backed.  In  the  case  of  dummies  this  flange  should 
extend  up  on  both  sides  of  the  tooth. 

The  Goslee  tooth  is  made  with  a  slot  on  each  side  that  inclines  from 
the  base  toward  the  occlusal  surface,  and  provides  for  the  extension  of 
the  backing  and  its  union  to  adjoining  backing  in  soldering.  Fig.  647 
shows  Goslee  teeth  unbacked  and  Fig.  648  backed.  Fig.  649  is  a  bridge 
supporting  a  lateral. 

In  the  construction  of  a  bridge  the  base  of  a  dummy  crown  when 
fitted  should  be  ground  enough  to  provide  room  for  the  backing,  also  to 
correspond  to  the  surface  of  the  model.  When  fitted  on  the  model, 
the  further  work  is  simplified  by  supporting  the  dummies  with  wax  in 
exact  position  and  covering  their  labial  or  buccal  sides  with  a  removable 


Pig.  647. 


Fig.  646. 


Pig.  648. 


Pig.  649. 


plaster  matrix,  to  permit  their  removal  and  replacement.  The  dummies 
and  all  wax  present  on  "them  and  on  the  surface  of  the  model  are  then 
removed.  Cover  the  space  between  the  abutments  with  tin  foil  and 
vaselin  its  surface,  to  prevent  further  adhesion  of  the  wax  in  the  ad- 
justment. Replace  the  dummies  in  the  matrix  to  ascertain  if  there  is 
sufficient  space  for  the  backings;  if  not,  provide  it  by  trimming  the 
porcelain.  Back  the  dummies,  adjust  them  in  position,  and  cement 
the  backings  and  cusps  of  the  crowns  with  wax.  Insert  a  piece  of  wire 
lengthwise  in  the  wax  to  act  as  a  brace  (see  Fig.  555).  Chill  the  wax, 
detach  the  plaster  matrix  and  remove  the  porcelain  crowns  and  dum- 
mies from  the  backings.  Examine  and  fill  in  with  wax  any  vacant 
places  between  the  backings.  Again  chill  the  wax,  carefully  remove 
wax  and  caps,  and  invest  in  the  manner  shown  in  Fig.  650.     In  solder- 


BRIDGE  CONSTRUCTION 


325 


ing,  all  the  joints  between  dummies  and  abutments  should  be  carefully 
united,  and  the  base  formed  by  the  surface  of  the  backings  reinforced 
sufficiently  to  reliably  sustain  the  strain  that  will  be  exerted  on  it  in 
occlusion.  When  the  bridge  is  properly  finished,  the  porcelain  teeth 
are  cemented  in  position. 


Fig.  650. 


Fig.  651 


Wlien  a  bridge  includes  two  or  more  dummies,  an  advisable  plan 
is  to  remove  two  at  a  time  from  the  matrix  and  solder  the  backings 
together.  When  the  several  dummies  are  united,  they  are  waxed 
fast  to  the  abutments,  removed  and  soldered  to  them.  In  this  way, 
warping  of  the  backing  is  avoided  which,  if  it  occurs,  prevents  the 


Pig.  653. 


Figs. 


porcelain  from  fitting  into  place  and  is  very  difficult  to  remedy. 
651  and  652  show  bridges  with  Goslee  teeth. 

Casting  Method. — The  base  of  the  porcelain  duminies  may  be  cast 
separately  (see  Part  III,  Chapter  XVI)  and  soldered  together  or  cast  in 
one  piece  and  then  united  to  the  abutments. 


Fig 


Cast  Sanitary  Bridge.— To  illustrate  this  method,  we  will  take  the 
case  illustrated  in  Fig.  653,  consisting  of  bicuspid  and  molar  dummies 
supported  by  gold  crowns  on  the  first  bicuspid  and  a  second  molar. 
The  space  between  the  crowns  on  the  model  of  the  case  is  filled  in  with 
plaster  as  a  support,  as  shown  at  A,  Fig.  654,  and  the  surface  of  the 


326 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


plaster  at  the  occlusal  side  is  given  a  concave  form,  to  impart  a  cor- 
responding oval  curve  to  the  surface  of  the  wax. 

The  surface  of  the  support  is  varnished  and  then  lubricated  to  pre- 
vent adhesion  of  the  wax.  The  wax  for  the  casting  model  is  placed  on 
the  support  between  the  crowns  and  the  antagonizing  teeth  occluded. 
The  wax  model  is  then  chilled,  trimmed,  shaped,  removed  and  cast. 
The  cast  gold  dummies  are  waxed  in  position  to  the  abutment  crowns, 
all  is  removed  and  abutment  crowns  and  dummies  united. 

The  curved  surface  of  the  base  of  the  dummies  permits  it  to  be  more 
easily  reached  and  cleaned  by  the  tooth-brush  than  a  flat  surface.  Fig. 
655  shows  the  completed  bridge. 


Pig.  655. 

Sanitary  Porcelain  and  Gold  Bridge 

In  this  style,  in  contradistinction  to  the  preceding  method,  the 
coronal  section  of  the  absent  teeth  is  restored  entirely  of  polished,  or 
better  still,  glazed  porcelain. 


Pig.  656. 

As  the  surface  of  porcelain  is  not  affected  by  the  secretions  and  as 
deposits  cannot  well  adhere  to  its  surface,  it  is  as  near  being  sanitary 
as  a  material  as  possible.     A  bridge  of  this  form  is  seen  in  Fig.  656. 


Pig.  657. 

Either  detached-post  crowns  or  English  tube  teeth  are  ground  and 
fitted  as  dummies  and  covered  on  the  buccal  side  with  a  plaster  matrix, 
as  seen  in  Fig.  657.  The  holes  in  the  center  of  the  porcelain,  when 
detached-post  crowns  are  used,  are  drilled  through  to  the  occlusal 
surface,  and  at  the  cervical  end  or  base  the  holes  are  closed  by  baking 


BRIDGE  CONSTRUCTION 


327 


into  them  porcelain  body.  A  high-fusing  body  should  be  used  so  that 
the  heat  required  to  fuse  it  will  be  sufficient  to  re-gloss  the  ground  sur- 
face of  the  porcelain.  The  occlusal  surfaces  are  then  ground  down  so 
as  to  provide  sufficient  space  for  the  thick  cusp-caps,  as  illustrated  in 


Pig.  658. 

Fig.  658.  The  cusp-caps  are  cast  with  posts  extended  into  the  holes  in 
the  dummies,  or  the  posts  are  afterwards  inserted  and  soldered.  The 
cusp-caps  are  adjusted  in  position,  and  the  ends  cemented  to  the  abut- 
ments with  wax,  and  the  bridge  removed.     The  porcelain  dummies  are 


Pig.  659. 

removed  from  the  cusp-caps  (Fig.  659,  in  section),  the  bridge  invested 
and  the  parts  soldered  together.  The  bridge  is  then  trimmed  and  pol- 
ished and  the  porcelain  dummies  cemented  in  position.  The  bridge  then 
appears  as  shown  in  Fig.  656. 


Pig.  660. 

The  cervical  sections  or  bases  of  upper  dummies  are  best  reduced  in 
size  and  given  a  surface  approximating  that  of  the  shape  of  the  gingival 
border  and  on  the  lower  jaw  more  of  an  oval  form,  as  seen  in  section 
in  Fig.  659.  To  avoid  exposure  of  metal,  and  for  esthetic  reasons, 
especially  on  superior  dummies,  the  cusp  or  metallic  portion  and  the 
porcelain  can  be  shaped  as  indicated  in  Fig.  660. 


CHAPTER^VII 


EXTENSION  BRIDGES 


GOVERNING  MECHANICAL  PRINCIPLES — CONSTRUCTION- — A  LUG  SUPPORT 
■ — A   LUG   ANCHOR   WITH   LOCK    PIN INTERVENING   ROOTS 

The  term  "Extension"  is  applied  to  bridges  chiefly  or  entirely  sup- 
ported by  one  abutment.  In  relation  to  the  anterior  teeth,  it  means 
attaching  a  dummy  to  an  artificial  crown,  or  other  form  of  retentive 
abutment  to  replace  an  adjoining  absent  tooth,  with  or  without  a  lug 
resting  on  an  adjoining  tooth  as  a  supporting  abutment.  A  bridge 
of  this  style  when  it  replaces  two  or  three  posterior  teeth  is  formed  by 
using  two  of  the  anterior  teeth  as  an  abutment,  and  extending  the 
dummy  teeth  from  it,  suspended,  or  on  a  saddle. 

A  saddle  is  an  oval-shaped  gold  or  platinum  plate  of  the  form  of 
the  alveolar  ridge,  placed  under  the  extension  dummy  teeth  for  them 
to  rest  on  and  obtain  alveolar  support  to  resist  direct  and  lateral 
stress  in  occlusion.  Although  a  most  serviceable  adjunct  to  a  remov- 
able bridge,  its  use  has  been  condemned  and  dispensed  with  in  fixed 
bridge-work,  as  being  insanitary.  When  a  metallic  base  is  applied 
under  a  dummy  tooth,  it  should  not  exceed  the  size  of  the  base  of  the 
dummy  and  be  of  a  form  that  will  permit  the  passage  of  floss  silk  between 
it  and  the  surface  of  the  gum  for  cleanliness  and  the  health  of  the  mem- 
brane. While  such  a  base — sometimes  incorrectly  termed  a  saddle — 
may  slightly  aid  to  steady  a  dummy,  it  furnishes  no  material  alveolar 
support. 

Governing  Mechanical  Principles. — In  extension  bridge- work,  the 
portion  that  constitutes  the  bridge  exerts  on  the  abutment,  in  resist- 
ing the  force  of  occlusion,  an  action  like  that  of  a  lever.  This  principle 
must  receive  consideration  in  the  employment  of  this  form  of  bridge. 
A  lug  support  or  supporting  abutment  on  the  extended  end,  if  attain- 
able, should  always  be  applied  even  to  one  tooth.  More  than  one 
tooth  should  not  be  extended  from  an  abutment  without  such  support. 
When  two  approximal  crowns  support  an  extension  bicuspid  or  molar 
bridge  dummy,  occlusal  force  on  the  dummy  is  counterbalanced  by  the 
resistance  of  the  further  anchorage  crown  from  the  bridge,  the  pressure 
on  which  is  in  a  line  from  the  socket  occlusally;  the  crown  approximal 
to  the  dummy  acting  as  a  fulcrum  the  force  on  which  is  in  the  di- 

328 


EXTENSION  BRIDGES 


329 


rection  of  the  apex  of  the  root.  The  occlusal  surface  of  the  bridge  tooth 
should  be  narrower  from  buccal  to  lingual  side  than  the  natural  tooth, 
to  offer  less  occlusal  surface  to  the  antagonizing  teeth,  between  which 

and  the  dummy  tooth,  there  should  be 
a  space  of  about  one-sixteenth  of  an 


Fig.  661. 


Pig.  662. 


inch.-    In  fact,  such  an  extension  dummy  tooth  should  be  inserted 
principally  for  appearance  and  not  for  actual  use. 


Pig.  663. 


Fig.  664. 


Construction. — The  abutment  is  first  constructed.  If  it  consists 
of  two  crowns  they  are  soldered  together.  An  articulation  and  im- 
pression are  taken  which  will  remove  the  abutment  in  position,  and 
models  are  made.  The  extension  tooth  or 
teeth  are  then  fitted  to  position  and  soldered 
to  the  abutment.  Figs.  661,  662,  663  and 
664  show  small  extension  bridges. 

A  Lug  Support. — This  consists  of  a  lug 
formed  at  the  end  of  an  extension  bridge  to 
rest  on  either  an  inlay,  a  gold  or  amalgam 
filling  in  the  adjoining  tooth,  or  the  surface 
of  the  tooth  acting  as  a  supporting  abutment. 
Fig.  665  illustrates  a  case  with  a  lug  resting 
on  a  cuspid. 

A  lug  support  is  formed  as  follows:  When  the  dummies  are  mounted 
on  the  model  ready  for  investment,  adapt  on  the  model  of  the  inlay 
filling  or  tooth  where  the  lug  is  to  rest,  a  piece  of  thin  platinum,  gage 
No.  36  to  38.  Place  on  the  surface  of  the  platinum,  when  adjusted,  a 
still  narrower  piece  of  gold  clasp  plate.     Wax  them  in  position  to  the 


Fig.  665. 


330 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


dummy  tooth  and  invest.  The  projecting  ends  of  the  platinum  and 
gold  plate  should  be  long  enough  to  extend  entirely  across  the  tooth  over 
on  the  adjoining  one,  to  furnish  a  means  of  retaining  the  metal  in  posi- 
tion in  the  investment  during  soldering.  The  wax  should  cover  only 
a  little  more  than  the  portion  of  the  metal  to  form  the  lug  when  sold- 
ered. In  finishing  the  surplus  metal  is  cut  off  and  the  lug  reduced  so  as 
to  extend  not  quite  to  the  edge  of  the  inlay  or  filling  it  rests  on.  Some- 
times in  the  case  of  an  incisor,  a  lug  is  allowed  to  rest  directly  on  the 


Pig.  666. 

lingual  side  of  the  adjoining  tooth  as  shown  in  Fig.  665.  A  lug  so 
applied  should  be  reduced  in  size  and  the  edge  slightly  rounded  so  that 
floss-silk  may  be  freely  passed  under  it,  which  should  be  done  at  least 
twice  daily.  In  the  case  illustrated  in  Figs.  666  and  667,  the  lug  rests 
with  the  end  curved  in  a  countersunk  amalgam  filling. 

A  Lug  Anchor  with  Lock  Pin. — This  consists  in  addition  to  a  lug 
of  a  pin  that  anchors  in,  but  is  not  cemented  in  the  inlay  or  filling  it 
rests  upon.     For  this  purpose  a  gold  inlay  or  amalgam  filling  is  inserted 


Pig.  667. 

in  a  deep  cavity  formed  in  the  side  of  a  tooth,  as  illustrated  in  Fig. 
668,  which  represents  a  typical  case.  The  filling  or  inlay  is  slightly 
countersunk  and  a  hole  is  drilled  in  the  center  about  one-sixteenth  of  an 
inch  in  depth,  large  enough  to  freely  receive  an  iridio-platinum  pin 
of  about  gage  No.  16.  A  disk  of  platinum,  gage  No.  36,  large  enough 
to  cover  the  filling,  is  adapted  to  its  surface  and  perforated  over  the 
orifice  of  the  hole.  The  point  of  the  pin  is  inserted  in  position  through 
the  hole  in  the  platinum,  into  the  hole  in  the  amalgam,  attached  with 
wax,  removed,  invested  and  connected  to  the  platinum  with  a  small 


EXTENSION  BRIDGES 


331 


quantity  of  pure  gold.  The  lug  is  trimmed  and  fitted  in  the  mouth,  the 
bridge  inserted  and  the  lug  attached  with  wax  to  the  bridge.  Bridge 
and  lug  are  removed,  invested,  united  and  the  lug  reinforced  with  solder 
and  a  narrow  strip  of  gold  clasf)  plate. 

A  supporting  abutment  as  constructed  for  removable  bridge-work 
and  described  in  Part  V,  Chapter  I,  may  in  some  cases  be  used  for  a 
fixed  bridge. 


Fig.  668. 

Connecting  Bars  for  Bridges. — Connecting  bars,  to  obviate  the 
removal  of  crowns  of  natural  teeth  intervening  between  the  sections  of 
a  bridge,  are  formed  by  passing  a  heavy  bar  of  round  or  oval  shaped 
clasp  gold  or  iridio-platinum  wire,  about  gage  No.  14,  around  the  inter- 
vening teeth,  close  to  but  not  touching  them,  and  resting  lightly  against 
the  gum,  so  as  not  to  cause  too  pronounced  interference  with  the  tongue 


This  is  accomplished  by  very  slightly  indenting  the  bar  in  the  surface  of 
the  model  before  soldering  (Fig.  669).  Waxed  floss-silk  should  be  daily 
drawn  under  such  a  bar. 

Intervening  Roots.^ — An  intervening  root  not  suitable  for  crowning, 
but  free  from  disease,  between  the  abutments  of  a  projected  bridge, 
when  necessary  and  practicable,  may  be  allowed  to  remain.  The  root 
is  to  be  given  preparatory  treatment  and  a  porcelain  or  gold  inlay  in- 


332 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


serted  that  will  cover  the  end  of  the  root  and  be  even  with  or  a  little 
above  the  surface  of  the  gum,  especially  on  the  lingual  side.     A  root  so 


Pig.  670. 


treated  can  be  utilized  to  afford  some  support  by  resting  the  bridge 
upon  it.  Fig.  670  represents  a  case  in  which  the  root  of  the  cuspid  on 
the  right  side  has  been  so  treated  and  utilized. 


CHAPTER  VIII 

BRIDGE-WORK  AND  SPLINTING  IN  CASES  OF  PYORRHEA  ALVEOLARIS 

THE    PLATE    AND    PIN    ATTACHMENT — USE    OF    CONNECTING    COLLARS — 
POSTERIOR   TEETH — ^BICUSPIDS    AND    MOLARS 

In  cases  of  pyorrhea  alveolaris,  when  the  teeth  are  loose,  connecting 
them  with  bridge-work  or  a  spHnt  steadies  them  in  their  sockets  and 
consequently  permits  more  effective  treatment. 

The  method  here  described  relates  to  teeth  not  affected,  or  only 
slightly  so  by  decay. 


Fig.  671. 

The  Plate  and  Pin  Attachment. — This  attachment  may  occasionally 
be  applied  in  cases  of  pyorrhea  alveolaris.  By  its  use  loosened  teeth 
can  be  joined  together  and  supported  without  exposure  of  metal. 


Fig.  672. 

In  such  cases,  when  the  tooth  has  a  vital  pulp,  a  plate  with  two  or 
three  pins  is  used,  and  when  the  tooth  is  pulpless  one  pin.  The  pins  and 
plates  are  made  and  fitted  to  each  tooth,  the  ends  of  the  pins  being  left 
protruding  from  the  plates.     An  impression  is  taken,  removing  the 

333 


334 


CROWN;  BRIDGE;  AND  PORCELAIN-WORK 


plates  and  pins  in  position.  They  are  next  invested  and  soldered 
together.     (See  Part  IV,  Chapter  IV.) 

An  intervening  absent  tooth  or  teeth  may  be  supported  between 
sections  of  the  plates. 

The  method  is  especially  applicable  in  cases  involving  the  lower 
front  teeth.  Fig.  671  illustrates  such  a  case  with  the  teeth  prepared, 
pulps  having  been  removed;  Fig.  672  the  plates  with  their  projecting 
posts  in  position;  Fig.  673  the  constructed  denture,  and  Figs.  674  and 
675  the  denture  in  position  on  the  teeth. ^ 


Pig.  673. 

Use  of  Connecting  Collars. — ^Fig.  676  illustrates  and  explains  a 
method  of  replacing  an  incisor  and  supporting  the  adjoining  loosened 
teeth  with  successive  cemented  connecting  collars  of  gold,  in  cases  of 
pyorrhea  alveolaris.  This  method  does  not  require  removal  of  the 
pulp.  For  the  application  of  such  collars,  the  teeth  require  to  be  trim- 
med the  thickness  of  the  plate  used.  The  collars  may  be  formed  of  a 
strip  of  pure  gold  plate  about  gage  32  to  7,;^,  or  platinum,  gage  Nos.  36 


Fig.  675. 

to  38,  by  bending  and  fitting  the  strips  to  the  form  of  any  two  teeth,  in 
the  shape  shown  at  A,  Fig.  677.  This  leaves  but  one  thickness  of 
plate  between  the  teeth.  An  additional  loop  can  then  be  added,  as 
shown  at  B,  for  one  adjoining  tooth.  The  soldering  may  be  done 
quickly  with  a  Bunsen  burner  without  investing.  Parts  of  the  loops 
which  demand  it  should  be  slit  and  lapped  to  allow  the  plate  to  be 
adapted  closely  to  the  surface  of  the  tooth. 
1  Dr.  D.  D.  Smith. 


BRIDGE-WORK  AND  SPLINTING 


335 


The  bands  of  metal  should  be  })laced  toward  the  incisal  section  of 
the  teeth,  leaving  the  interproximal  spaces  between  the  teeth  enturely 
free.  The  cementation  can  be  done  with  zinc  phosphate,  or  if  removal 
is  contemplated,  with  gutta-percha  cement.  A  fusible  metal  die  will 
assist  the  operation  before  fitting  the  collar  in  the  mouth.  To  form 
the  metal  model,  take  a  plaster  impression  in  a  sectional  impression 
cup,  and  fill  with  fusible  metal.  Cut  the  spaces  between  the  teeth  on 
the  model  with  a  saw  of  the  same  gage  as  the  gold  or  platinum  plate  to 
be  used. 


Fig.  676. 


Fig.  677. 


Posterior  Teeth 

Bicuspids  and  Molars. — ^These  teeth  may  be  bridged  or  splinted 
by  the  use  of  inlays,  bars  or  small  caps  or  plates.  Pins  should  be 
inserted  in  the  mesial  and  distal  ends  of  an  inlay  or,  if  pulpless,  a  single 
post  can  be  extended  into  the  pulp-canal.  Sufi&cient  of  the  natural 
crown  and  of  the  antagonizing  teeth  must  be  removed  to  allow  ample 
space  for  the  intervening  metal  applied. 


Fig.  678. 


Fig.  679. 


Fig.  680. 


Fig.  678  shows  in  section  a  molar  with  living  pulp  in  which  is  inserted 
a  bar  or  inlay,  with  two  pins  in  the  line  of  the  sulci,  and  the  inlay  or  bar 
extended  into  an  adjoining  pulpless  molar.  Fig.  679  represents  in 
section,  viewed  from  the  lingual  side,  a  small  plate  and  pin  attachment 
on  a  pulpless  cuspid  and  bicuspid. 

Fig.  680  and  681  illustrate  in  section  pulpless  bicuspids  and  molars 
prepared  with  an  iridio-platinum  bar,  with  pins  to  be  inserted  and 
anchored  in  them  with  amalgam.     Veneering  the  bar  with  a  film  of  pure 


336 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


gold  by  melting  pellets  of  gold  foil  over  it  with  a  blowpipe,  then  rolling 
it  under  a  file,  will  facilitate  a  better  adhesion  of  the  amalgam  to  the  bar. 
In  the  formation  and  adjustment  of  these  applicances,  close  adapta- 
tion of  the  metal  to  the  surface  of  the  teeth  and  avoidance  of  pockets 
should  be  observed.     The  incisal  edges  and  cusps  of  affected  teeth 


Pig.  68i. 


Fig.  682. 


should  be  trimmed  and  shortened  so  that  while  the  teeth  occlude  evenly, 
the  cusps  only  touch  their  antagonizing  teeth  in  the  lateral  movements 
of  the  jaw.  The  object  is  to  retain  direct  pressure  but  do  away  with 
lateral  strain  (See  Fig.  682).  Constant  care  regarding  cleanliness  by 
the  frequent  and  regular  practice  of  prophylactic  measures  is  required 
of  the  patient.     (See  Part  IV,  Chapter  XL) 


CHAPTER  IX 

REPAIR  OF  CROWN-  AND  BRIDGE-WORK 

THE  ORDINARY  METHOD — DR.  BRYANt'S  METHOD — COUNTERSUNK  PIN- 
HOLE METHOD — TO  REPAIR  WITH  A  DIMELOW  FACING — ASH'S  RE- 
PAIR FACINGS — INLAY  METHOD — REPAIR  OF  AN  INCISOR  OR  CUSPID 
GOLD-BACKED  CROWN  WITH  A  DETACHED-POST  CROWN — ADVANTAGES 
OF  DETACHABLE  BRIDGE-WORK — REMOVAL  OF  CROWNS  OR  BRIDGES 
CEMENTED    WITH    ZINC    OXYPHOSPHATE — REMOVAL    OF    A    POST — A 

POST    PULLER — DIFFICULT    POST    REMOVAL REMOVAL    OF     CROWNS 

OR  BRIDGES   CEMENTED   WITH  GUTTA-PERCHA,   ALONE  OR  COMBINED 
WITH    OXYPHOSPHATE — REPAIR  OF  A  GOLD  COLLAR  CROWN 

The  fracture  of  a  porcelain  facing  on  a  permanently  attached 
bridge  is  an  annoying  incident  for  both  patient  and  dentist.  It  is 
usually  attributable  to  failure  to  properly  protect  the  incisal  edge  or 
occlusal  surface  of  the  porcelain  with  metal,  a  precaution  rendered 
necessary  by  the  rigid  character  of  the  resistance  offered  the  antag- 
onizing teeth  through  the  abutments,  or  by  exposure  of  the  porcelain 
in  time  through  loss  by  attrition  of  the  metal  protecting  it.  In  most 
cases  the  porcelain  can  be  replaced  without  the  removal  of  the  bridge, 
but  the  attachment  is  seldom  as  reliable  as  in  the  original  piece. 

The  Ordinary  Method. — The  following  is  the  method  commonly 
adopted  with  incisors  or  cuspids:  The  pins  of  the  broken  facings  are 
cut  off,  the  surface  of  the  backings  trimmed  level,  and  a  suitable  long- 
pin  facing  selected.  Mark  the  position  of  the  pins  of  the  new  facing 
on  the  backing  by  drying,  heating  and  flowing  over  its  surface  a  film 
of  wax,  then  with  small  pliers  place  the  facing  in  position,  and  press  the 
pins  in  the  wax;  or  place  a  little  rouge  and  oil  on  the  end  of  the  pins  and 
mark  the  backing  with  them.  At  the  points  marked,  drill  holes  in  the 
backing  to  receive  the  pins  of  the  new  facing,  countersinking  the  holes 
at  the  lingual  side.  After  the  backing  is  drilled,  grind  the  porcelain 
to  fit  it  as  perfectly  as  possible,  place  in  position  and  grind  off  the  pins 
so  that  they  protrude  enough  to  form  a  head  when  riveted. 

If  a  suitable  long-pin  tooth  is  not  procurable,  the  short  pins  of  an 
ordinary  tooth  can  be  lengthened  by  bending  a  piece  of  platinum 
wire  in  the  form  of  a  semicircle  and  soldering  its  ends  to  the  ends  of  the 
pins  with  pure  gold.  The  wire  is  then  cut  in  the  center  and  the  length- 
ened pins  trimmed  as  required. 

22  337 


338  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

The  pins  are  riveted  on  the  h'ngual  side  into  the  countersunk  holes 
of  the  backing.  The  riveting  should  be  done  with  punch  forceps  hav- 
ing a  large  punch  (Fig.  683),  the  porcelain  facing  being  protected  by  a 
piece  of  lead  placed  against  the  labial  aspect,  or  by  the  use  of  a  matrix 
formed  of  impression  compound  softened  and  then  chilled.  The  heads 
of  the  pins  should  be  burnished  smooth  with  a  revolving  burnisher. 

In  case  of  fracture  of  the  porcelain  facing  of  a  bicuspid  crown  or 
dummy  with  a  thick  gold  backing,  a  corresponding  facing  with  very  long 


Pig.  683. 

pins  is  selected  and  ground  to  fit,  and  holes  in  proper  position  drilled 
in  the  gold,  to  receive  the  full  length  of  the  pins.  Roughen  the  pins  a 
little  with  a  sharp  instrument  and  cement  pins  and  facing  to  the  gold. 
Should  the  holes  extend  through  the  gold  at  the  lingual  side,  the  open- 
ing should  be  slightly  countersunk  and  filled  with  gold  or  amalgam. 
Any  gold  present  to  protect  the  occluding  edge  of  the  porcelain  should 
be  burnished  against  its  surface. 

The  Improved  Bryant  Method 

The  technic  of  the  Bryant  bridge-repair  method,  as  recently  modi- 
fied, to  assure  easier,  more  accurate  work,  and  greater  strength  is  thus 
described : 

Clip  off  the  pins  from  the  bridge  and  grind  to  a  flat  surface,  and 
cover  the  surface  with  a  film  of  wax.  Hold  the  new  facing  in  exact 
position  and  press  the  pins  through  the  film  of  wax.  With  a  pointed 
instrument  and  hand  mallet  center-punch  the  position  of  the  pins  as 
shown  in  the  wax,  thus  giving  a  starting  point  for  the  drill  No.  loi  (Fig. 
684),  with  which  drill  two  holes  through  the  backing  to  receive  the 
pins  of  the  new  facing.     Next  grind  the  facing  to  exactly  fit  the  surface 


REPAIR  OF  CROWN-  AND  BRIDGE-WORK 


339 


of  the  backing,  and  with  counterbore  No.  lo  enlarge  the  holes  in  the 
backing. 

Using  reamer  No.  3A,  from  the  lingual  side,  enlarge  the  lingual 
opening  of  the  holes,  taking  care  to  stop  this  operation  just  before  the 
end  of  the  reamer  is  flush  with  the  labial  surface  of  the  backing.  Care- 
fully cut  a  shallow  thread  on  the  tooth  pins  with  die  No.  i  and  follow 
with  die  No.  2  to  complete  the  thread  to  full  depth.  See  that  the  pins 
are  threaded  their  full  length  close  up  to  the  porcelain. 

Cover  the  lingual  surface  of  the  facing  with  cement  or  gutta-percha, 
keeping  the  pins  clean,  and  press  to  place.  Use  nut-holder  No.  6  to 
carry  the  nuts  No.  5  to  place  over  the  threaded  pins,  and  with  nut- 


FlG.  684. 

driver  No.  4  screw  alternately  to  seat.  The  nuts  should  be  tightened 
sufficiently  to  bring  the  facing  and  backing  into  contact,  but  without 
excessive  force,  which  might  cause  fracture  of  the  porcelain. 

If  the  nut  or  pin  extend  beyond  the  backing,  grind  off  flush  and 
polish.  If  below  the  surface  of  the  backing,  fill  in  with  Corona  gold  or 
gold  foil. 

Countersunk  Pin-Hole  Method. — This  method  is  to  be  used  only 
when  the  pins  remain  intact  in  the  backing.  Remove  all  the  fractured 
facing.  Select  a  facing  of  the  same  make  and  mold;  if  not  procurable, 
one  of  the  same  size,  thickness  of  porcelain  and  location  of  pins.  Cut  the 
pins  off  close  to  the  porcelain;  drill  out  the  portion  of  the  pins  left  and 


340 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


enlarge  and  slightly  countersink  the  holes  with  carborundum  paste 
and  a  copper  or  steel  drill/  so  that  the  pins  in  the  backing  shall  enter 
the  holes  in  the  porcelain  facing  easily  and  permit  the  new  facing  to 
come  to  place,  as  shown  in  Fig.  685.  To  correct  any  discrepancies  in 
conformation  between  the  surface  of  the  gold  backing  and  the  facing, 
paint  the  surface  of  the  gold  with  a  coat  of  rouge  and  oil  and  press  the 
facing  against  it.  The  rouge  will  mark  on  the  porcelain  the  exact  spot 
to  remove.  When  Mitted  by  this  method  and  cemented  with  zinc  oxy- 
phosphate  or  silicate  cement,  a  very  reliable  replacement  of  the  facing 
is  effected. 

To  Repair  with  a  Dimelow  Facing. — A  Dimelow 
facing  may  be  utilized  to  replace  a  fractured  facing 
of  the  ordinary  type  when  the  pins  are  broken  from 
the  backing.  Clear  the  backing  of  fractured  porce- 
lain and  pins.  Select  a  Dimelow  facing  (See  Fig.  592) 
and  grind  it  to  position  against  the  backing.  Dry 
and  heat  the  backing  and  melt  a  little  wax  over  the 
part  that  corresponds  to  the  position  of  the  pin-holes 
in  the  facing.  Moisten  the  facing  and  press  it  firmly 
against  the  wax.  On  removal,  the  position  for  the  pin-holes  through 
the  backing  will  be  indicated  by  two  raised  points  of  wax,  formed  by 
the  holes  in  the  facing.  With  a  spear-shape  drill  corresponding  in 
size  to  the  holes  in  the  porcelain,  drill  two  holes  through  the  backing 
in  the  places  indicated  by  the  wax  points  in  a  linguo-gingival  direction, 
in  a  line  with  the  holes  in  the  facing.  Follow  the  drill  with  a  tap,  and 
screw  into  the  holes  two  threaded  pins,  and  cement  facing  to  pins  and 
backing.^ 


Pig.  685. 


Fig.  686. 


Ash's  Repair  Facings. — Fig.  686  illustrates  these  facings.  They 
are  made  with  a  slot  for  the  ends  of  the  pins  of  the  broken  porcelain 
facing  to  fit  into  and  be  connected.  As  the  position  of  the  pins  usually 
varies,  the  replacement  may  call  for  considerable  fitting.  This  can  be 
simplified  as  follows:  After  removing  all  remnants  of  the  broken  facing 
and  exposing  the  pins,  place  a  little  cement  around  the  shanks  of  the 

1  Use  one  of  the  drills  of  the  set  sold  for  drilling  holes  in  porcelain  teeth  to  insert 
imitation  gold  filling. 

^  An  especially  prepared  outfit  is  manufactured  and  sold  for  repairing  with  the 
Dimelow  facing. 


REPAIR  OF  CROWN-  AND  BRIDGE-WORK  341 

pins  to  even  them  with  the  heads,  then  take  an  impression  of  the  back- 
ing and  pins  with  impression  compound,  and  form  an  amalgam  replica 
or  model  (Fig.  687).  Place  some  white  gutta-percha  in  the  place  of  the 
porcelain  to  represent  the  facing  and  dismiss  the  patient.  By  the 
next  engagement,  grind  and  fit  an  Ash  porcelain  facing  to  the  amalgam 
model,  a  much  easier  task  than  fitting  it  to  the  backing  in  the  mouth. 
Cement  facing  in  position  with  silicate  cement. 

Inlay  Method. — This  method  is  applicable  if  the  pins  are  still  in 
the  backing.  Select  porcelain  facing,  if  possible  of  the  same  mold  as 
the  fractured  facing.  Remove  the  pins  of  the  facing,  and  using  as  a 
model  an  amalgam  replica  made  as  described  in  the  preceding  method 
(Fig.  687),  grind  down  the  facing  to  a  veneer  that  will  fit  in  position 
over  the  pins  of  the  backing.  Adapt  by  burnishing  to  the  surface  of 
the  cavity  of  the  backing  that  was  occupied  by  the  porcelain,  a  piece 
of  i/ioQo  platinum  foil,  as  a  matrix,  and  if  necessary,  by  swaging  the 
platinum  to  the  amalgam  die.  Shape  the  platinum  over  the  pins  but 
not  in  on  the  sides  so  as  to  obstruct  easy  removal 
of  the  matrix.  Fill  the  matrix  with  Close's  porce- 
lain body.  Vibrate  the  body  and  absorb  the 
moisture  with  blotting  paper,  then  press  the  porce- 
lain veneer  on  the  surface  and  into  the  porcelain 
body  to  proper  position.  Remove  the  porcelain 
veneer  so  as  to  leave  the  impression  in  the  porce- 
lain body,  then  remove  matrix  and  body  from  the 
mold,  place  it  on  pulverized  silex  on  a  slab  and  give  it  a  good  biscuit 
bake. 

Replace  matrix  in  amalgam  model,  correct  any  warping  incidental 
to  the  shrinkage  in  baking,  add  body  and  again  place  the  veneer 
in  position.     Remove  both  together  and  give  the  fusing  bake. 

When  the  platinum  matrix  is  removed  from  the  body  of  porcelain, 
you  have  a  porcelain  facing  the  exact  form  of  the  cavity  of  the  backing. 
The  cavity  or  box  in  the  porcelain  that  receives  the  pins  may  be  slightly 
countersunk  with  an  old  wheel  bur  and  carborundum  powder.  Cement 
to  place  with  silicate  cement  and  burnish  the  incisal  edge  of  the  gold 
backing  to  the  incisive  edge  of  the  porcelain. 

Repair  of  an  Incisor  or  Cuspid  Gold-Backed  Crown  with  a  De- 
tached-Post Crown. — Remove  fractured  porcelain  and  pins,  grind  and 
shape  the  gold  backing  and  floor  of  the  cap  as  nearly  as  possible  to  a 
form  approximating  that  of  a  gold  root-cap,  with  a  post  to  receive  a 
detached-post  crown.  Fig.  688  shows  the  relative  comparison.  Take 
an  impression  in  compound;  cut  and  shape  a  piece  of  coin  silver  the 
size  of  the  trimmed  post  on  the  root-cap,  insert  the  piece  of  coin  silver 


342 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Fig. 


in  the  impression  of  the  post  and  make  an  amalgam  die.  Allow  the 
amalgam  to  crystaUize  until  the  next  day.  Select  a  suitable  detached- 
post  crown.  As  the  post  on  the  cap  will  be  found  a  little  back  of  the 
line  of  the  hole  in  the  porcelain  in  a  lingual  direction,  remove  with 
fissure-shaped  carborundum  points  enough  porcelain  to  freely  admit 
the  post.  Should  the  carborundum  point  go  through  the  porcelain  in 
making  the  space  for  the  post,  trim  off  a  little  of  the  end  of  the  post  and 
bake  over  the  hole  a  thin  layer  of  Close,  Jenkins  or  other  suitable 
porcelain  body.  If  necessary,  build  the  applied 
body  a  little  above  the  surface  of  the  porcelain 
of  the  crown,  as  shown  in  section  at  point  A, 
Fig.  689.  The  post  is  notched  and  the  crown 
cemented  on  with  silicate  or  some  equally  hard 
cement,  that  will  adhere  to  the  porcelain  and 
gold. 

In   suitable  cases,  this  method  gives  very 
satisfactory  results  and  is  often  equal  in  re- 
liabihty  to  an  entire  new  crowning  operation. 

Silicate  Cement. — ^This  cement  can  be  used  to  temporarily  replace 
a  porcelain  facing.  When  the  metallic  incisal  edge  of  the  backing  or 
occlusal  surface  and  the  pins  are  present,  repair  work  of  considerable 
durability  may  be  effected.  The  fractured  porcelain  having  been  re- 
moved, the  backing  is  protected  from  moisture,  and  a  mixture  of  the 
silicate  cement  of  the  proper  shade  applied  and  shaped  with  a  spatula 
to  the  form  of  the  former  porcelain  facing.  When  the  cement  has  set 
it  is  shaped  in  detail.  A  matrix  approximating  the 
facing  in  form  may  be  used  to  condense  and  shape  the 
cement  when  setting. 

Advantages  of  Detachable  Bridge-Work.— If  the 
character  of  the  break  in  a  porcelain  facing  will  not 
permit  repair  in  the  mouth,  the  bridge  must  be  re- 
moved, repaired  and  reinserted.  Under  such  circum- 
stances, the  advantages  of  a  detachable  form  of  bridge 
are  evident.  The  additional  time  required  to  construct 
cases  of  bridge-work  that  will  properly  admit  of  being  made  detach- 
able and  cemented  with  gutta-percha  or  gutta-percha  cement  combined 
with  oxyphosphate  is  not  as  much  as  that  which  would  be  consumed 
in  the  construction  of  the  same  work  with  replaceable  porcelain  facings. 
Removal  of  Crowns  or  Bridges  Cemented  with  Oxyphosphate. — 
When  it  is  necessary  to  remove  an  artificial  incisor  or  cuspid  crown, 
whether  inserted  singly  or  as  a  support  for  a  bridge,  it  can  be  detached 
by  grinding  the  gold  or  porcelain  away  at  the  lingual  section  over  the 


Fg.  689. 


REPAIR  OF  CROWN-  AND  BRIDGE-WORK 


343 


post,  which  when  exposed  is  severed,  and  the  attachment  of  the  cement 
broken  up,  as  shown  at  A,  Fig.  690.  In  a  case  where  the  facing  is 
fractured  or  absent,  as  illustrated  in  Fig.  691,  the  post  may  be  more 
easily  reached  from  the  labial  side  (B).  The  collar  may  also  be  sUt 
and  bent  aside,  if  found  necessary.  When  a  post  of  a  crown  is 
veneered  with  a  film  of  gutta-percha  previous  to  cementation,  the  re- 
moval of  the  post  is  easily  effected. 

In  the  case  of  an  all-gold  crown,  usually  the  collar  on  one  or  both 
sides  has  to  be  divided  and  pried  up 
from  the  root  by  first  making  a 
groove  with  a  small  vulcarbo  disk, 
and  then  cutting  the  gold  with  a 
small  bur  and  a  sharp  instrument. 
A  crown-slitter,  an  instrument  made 
for.  the  purpose,  will  facilitate  the 
operation  (Fig.  692).  In  an  all-gold 
crown  on  a  very  short  posterior 
tooth,  a  large  hole  drilled  in  the 
grinding  surface  will  sometimes  admit 
of  removal  of  a  sufiicient  quantity 
of  the  cement  to  enable  the  attach- 
ment to  be  loosened  by  prying  up- 
ward. With  care  and  patience  in 
the  operation   of  removing  a  gold 


Pig.  690. 


Pig.  691. 


Pig.  692. 


crown,  it  will  often  not  be  injured  beyond  repair,  but  usually  the  time 
spent  in  repairing,  considering  the  result,  suggests  a  new  crown  instead. 

Removal  of  Post.^ — To  remove  a  post,  first  drill  away  the  cement 
around  the  post  at  the  orifice  and  a  short  distance  up  the  canal  with 
the  smallest  size  round-head  bur,  keeping  the  bur  against  the  surface 
of  the  post.  Next  seize  the  end  of  the  post  with  phers  and  with  a 
moderate  amount  5f  force  carefully  applied  endeavor  to  remove  it. 
If  this  does  not  succeed,  use  a  post  puller. 

A  Post  Puller.— Fig.  693  illustrates  the  S.  S.  White  post  puller 
outfit.     It  consists  of  a   straight  (i)  and  right-angle  (2)  reamer  to 


344 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


ream  the  end  of  a  post  (3)  and  a  screw  stock  to  cut  a  thread  on  the 
reamed  end.  The  screw  socket  of  the  puller  is  next  screwed  on  the 
end  of  the  post,  the  thumb-screw  that  lifts  the  socket  is  screwed  down 
against  the  end  of  the  root,  and  the  socket  of  the  post  lifted  incisally, 


(^ 

I  A  B  C  4 

■  Fig.  693. — Trepine  for  direct  aand  2,  Trephine  for  angle  handpieces.  3,  Screw- 
stock.  4,  Post-extractor.  A'  h,  C,  D,  Post  and  root  at  various  stages  of  the 
operation. 

removing  the  post.  A  rubber  washer  around  the  socket  with  a  metal 
washer  behind  it  ag?jnst  the  body  of  the  puller,  gives  the  necessary 
bearing,  equalizes  tne  pressure  and  avoids  fracture  of  the  root  by  cush- 
ioning it. 

Fig.  694  shows  another  style  of  post  puller,  called  the 
"Little  Giant,"  that  can  be  quickly  apphed  when  the 
end  of  the  post  extends  beyond  the  surface  of  the  end  of 
the  root.     The  end  of  the  post  is  seized  between  the  /_\ 

large  ■  beaks  of  the  puller  by  tightening  them  with  a 


Pig.  695. 

screw  and  the  shoulder  is  screwed  down  on  the  end  of  the  root,  lifting 
the  post  incisally. 

Difficult  Post  Removal. — Some  posts  are  so  deeply  inserted  and 
firmly  cemented  that  they  cannot  be  safely  removed  with  a  post 
puller  as  ordinarily  apphed.  In  such  cases  a  very  small  space  should 
be  cut  around  the  post,  removing  any  cement  present  and  as  Httle 


REPAIR  OF  CROWN-  AND  BRIDGE-WORK 


345 


dentin  as  possible,  with  the  smallest  sized  round-head  bur.     A  post 
puller  can  then  usually  be  effectively  applied. 

When  a  post  cannot  be  removed  by  any  of  the  methods  mentioned 
the  only  resource  is  to  drill  it  out, 
a  tedious  operation  and  one  re- 
quiring great  care.  In  the  upper 
section  of  the  canal  where  the  post 
cannot  be  seen  while  drilling,  use 
a  new  sharp  round-headed  bur. 
Apply  the  bur  with  a  light  steady 
pressure  that  will  indicate  when 
the  bur  is  on  the  metal  of  the 
post,  and  when  off  of  it  in  the 
dentin.  By  taking  time  and  ex- 
ercising patience,  the  post  can  be 
removed  without  material  injury 
to  the  root.  Smooth-sided  drills 
with  several  small  blades  that 
cut  only  on  the  end,  as  shown  in 
Fig.  695  may  be  used  effectively 
to  cut  into  the  center  of  the  post 
in  the  lower  section  of  the  canal. 

Removal  of  Crowns  or  Bridges 
Cemented  with  Gutta-Percha 
Only  or  Combined  with  Ox3rphos- 
phate. — In  metallic  collar  or  cap- 
crowns,  first  slightly  raise  the  edge 
of  the  collar.  Fig.  696  shows  a 
crown-heater  for  cementation  and 
removal  of  incisors  and  cuspids. 
It  is  to  be  moderately  heated  and 
applied  as  illustrated.  Fig.  697 
shows  a  small-sized  crown-heater 
for  general  use.  The  membrane 
should  be  protected  by  spreading 
a  napkin  across  the  mouth  over 
the  lower  lip.  In  using  the  form 
of  heater  shown  in  Fig.  697  heat 
it  almost  to  a  red  heat,  place  a 


Fig.  696. 


finger  against  the  artificial  crown  and  apply  the  crown-heater  to  the 
crown.  For  bicuspids  and  molars,  apply  the  crown-heater  to  the 
occlusal  surface  and  for  incisors  and  cuspids  at  the  lingual  side  toward 


346 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


the  incisal  edge.  As  the  crown  absorbs  the  heat,  it  is  indicated  by 
the  finger.  When  the  heat  is  raised  as  high  as  the  finger  can  comfort- 
ably bear,  the  crown-heater  should  be  removed  for  an  instant  to  permit 
the  crown  to  cool  slightly,  then  again  applied.  In  heating  a  crown,  it  is 
well  to  instruct  the  patient  to  raise  the  left  hand  should  the  heat  become 
painful  at  any  time.  The  application  of  the  heat  should  be 
continued  as  directed  for  at  least  three  to  five  or  more 
minutes  until  the  gutta-percha  in  all  parts  of  the  crown  is 
thoroughly  softened,  which  proceeds  slowly  owing  to  its  con- 
tact with  the  natural  crown  or  root.  In  bridge-work,  as  soon 
as  the  first  crown  is  heated,  instantly  pass  the  crown-heater 
along  the  surface  of  the  bridge  to  another  crown  or  crowns 
and  then  back  and  forth  on  the  surface  of  the  bridge  until  all 
the  attachments  are  uniformly  heated.  When  this  has  been 
effected,  start  the  bridge  at  one  end  and  then  at  the  other, 
or  at  both  together,  and  lift  it  from  position. 

Repair  of  a  Gold  Collar  Crown. — A  hole  or  slit  in  a  gold 
collar  or  crown  is  easily  repaired,  by  first  placing  and  press- 
ing on  the  outer  surface  over  and  into  the  hole  or  slit  soft 
adhesive  wax,  (W,  Fig.  698).  Next  adapt  a 
piece  of  platinum  foil  (PF)  larger  than  the 
aperture  on  the  inside  close  against  the  sur- 
face and  extended  beyond  the  edge  of  the 
collar,  and  attach  it  to  the  wax  by  placing 
a  hot  instrument  against  the  surface  of  the 
platinum  inside  the  crown.  The  interior  of 
the  crown  is  next  filled  with  investing  material.  The  wax  is  washed 
off  the  outside  of  the  crown,  exposing  the  hole  or  slit,  and  solder  is 
melted  and  flowed  over  the  platinum  and  gold  collar.  ITie  crown 
should  be  heated  slowly  to  allow  the  investment  to  dry  out  thoroughly 
before  the  soldering  is  begun. 


In  miniature. 
Fig.  697. 


Pig.  698. 


CHAPTER  X 
GENERAL  APPLICATION  OF  FIXED  CROWN-  AND  BRXDGE-WORK 

CENTRAL  OR  LATERAL  INCISORS,  CUSPIDS  OR  BICUSPIDS — CENTRALS, 
LATERALS  AND  CUSPIDS  COMBINED — CUSPIDS,  BICUSPIDS  AND  MOLARS 
COMBINED — BICUSPIDS  AND  MOLARS  COMBINED — USE  OF  PARTIAL 
CAP — ^INCISORS,  CUSPIDS,  BICUSPIDS  AND  MOLARS  COMBINED — EXTEN- 
SIVE APPLICATION  OF  FIXED  CROWN-  AND  BRIDGE-WORK — CRITICISM 

The  construction  and  general  application  of  fixed  bridge-work,  as 
explained  in  the  foregoing  chapters,  are  additionally  explained  and 
illustrated  in  the  following  typical  cases. 

Central  or  Lateral  Incisors,  Cuspids  or  Bicuspids. — The  restora- 
tion of  a  central  or  lateral  is  an  operation  that  calls  for  the  exercise  of 
judgment  and  in  some  methods  of  procedure,  tests  the  skill  of  the 
operator.  When  the  other  teeth  are  present,  the  subject  of  support 
involves  the  question  of  the  mutilation  or  excision  of  one  or  both  the 


adjoining  natural  crowns.  The  condition  of  the  adjoining  teeth 
respecting  freedom  of  the  crowns  from  decay,  whether  vital  or  pulpless, 
health  of  the  roots  and  contiguous  membranes  and  occlusion,  will 
suggest  the  most  suitable  method  of  procedure. 

When  a  central  is  to  be  replaced  and  a  normal  condition  of  teeth 
and  occlusion  is  present,  the  support  preferably  should  be  obtained  by 
the  adjoining  central,  or  central  and  lateral  combined,  if  possible  with- 
out removal  of  the  pulp.  If  the  abutment  tooth  is  favorable  in  form 
and  occlusion,  this  may  be  done  either  by  the  use  of  the  three-pin  plate 

347 


348 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


or  a  Carmichael  crown  on  the  central,  with  the  aid  of  a  lug  resting  on  the 
lateral.  The  three-pin  plate  is  frequently  suitable  in  the  case  of  a 
central.  Fig.  699  shows  a  typical  case.  A  is  the  bridge  viewed  from 
the  lingual  side  and  B  from  the  labial. 

When  the  central  is  short,  the  incisal  edge  worn  down  by  attrition 
so  that  the  dummy  tooth  will  have  to  resist  directly,  or  nearly  so,  the 
force  of  occlusion,  the  Carmichael  crown  is  preferable,  as  such  an  attach- 
ment is  comparatively  stronger.  An  anchorage  lug  resting  in  an  inlay 
in  the  lateral  is  also  advisable,  as  illustrated,  viewed  from  the  labial 
side  in  Fig.  700,  or  instead  the  use  of  another  Carmichael  crown  as  a 
support,  as  shown  in  Fig.  701,  lingual  aspect. 

If  either  the  central  or  lateral  is  pulpless,  an  inlay  or  plate  with  a 
post  extending  partly  up  the  pulp-canal  is  the  preferable  support,  as 
shown  in  Fig.  702. 

As  removal  of  a  pulp  to  form  an  attach- 
ment  involves    opacity  and    in    time    dis- 


FiG.  700. 


Pig.  701. 


Pig.   702. 


coloration  of  the  tooth,  it  should  be  avoided  if  possible  in  the 
case  of  young  patients.  In  the  case  of  patients  over  thirty  years  of 
age  discoloration  from  removal  of  the  pulp  need  not  be  so  seriously 
considered,  but  it  will  certainly  occur  to  some  extent  in  time,  no  matter 
how  scientifically  and  skilfully  the  operation  is  performed.  It  is  never- 
theless a  method  preferred  and  extensively  practiced.  Many  operators 
in  such  cases  remove  the  pulps  of  both  adjoining  teeth  to  insure  a  more 
positive  support  and  prevent  spreading  of  the  supporting  teeth,  also  to 
avoid  pressure  on  the  dummy  tooth  that  would  push  it  forward  and 
twist  the  central  on  its  axis  when  that  alone  is  used  as  the  abutment. 

When  a  puJp  is  to  be  removed  from  an  incisor  for  such  a  purpose, 
it  should  be  done  instantly  by  the  use  of  local  anesthesia  or  under  ni- 
trous oxid  alone  or  combined  with  oxygen.  The  upper  section  of  the 
root-canal  can  be  sealed  to  stop  all  hemorrhage  with  a  dressing  of  color- 
less essential  oil,  such  as  oil  of  myrtle,  or  Geminol,  a  highly  refined 
French  preparation  of  the  Eucalyptus  class.  The  rubber-dam  should 
be  applied,  no  saliva  allowed  to  enter  the  canal  and  the  dressing  herme- 
tically sealed  with  gutta-percha,  covered,  if  necessary,  with  oxyphos- 


FIXED  CROWN-  AND  BRIDGE-WORK 


349 


phate.  The  dressing  should  be  removed  within  three  days,  the 
extreme  end  of  the  canal  filled  with  gutta-percha  and  the  remainder 
of  the  canal  and  cavity  of  the  crown  filled  with  absolutely  white  zinc 
oxychlorid.  No  further  antiseptic  treatment  than  mentioned  should  be 
practiced,  as  the  canal  is  not  infected  and  only  needs  protection.  In 
this  manner  the  natural  color  of  the  tooth  will  be  maintained  to  the 
greatest  possible  degree.  Later  drill  out  enough  oxychlorid  to  admit 
the  retaining  post.  Fig.  703  shows  a  case  treated  in  this  manner,  the 
central  and  lateral  being  used  as  supports.  Fig.  704  illustrates  a 
lateral  and  central  supported  by  a  central  and  cuspid. 

Inferior  incisors  are  seldom  lost  except  by  pyorrhea.  In  such  a 
case,  plates  with  pins,  or  collars  may  be  used  on  the  adjoining  teeth,  as 
was  illustrated  in  Figs.  671  to  675.  When  an  open-face  crown  is  used 
as  an  abutment,  the  labial  surface  of  the  gold  needs  to  be  removed 
enough  to  avoid  its  exposure  in  the  movement  of  the  lips. 


Pig.  703. 


Pig.  704. 


The  pin-plate  method  is  described  in  Part  IV,  Chapter  III,  The 
pulps  of  the  teeth  in  the  mandible  require  to  be  removed  in  this 
method,  except  in  the  case  of  a  cuspid,  when  the  size,  shape  and  con- 
dition of  the  tooth  will  permit  of  the  insertion  of  three  pins. 

Excision  of  the  natural  crown  of  the  adjoining  central  and  mounting 
a  collar  crown  on  the  root  simplifies  the  operation  of  restoration  of 
either  a  central  or  lateral.  When  a  central  is  disfigured  or  weakened 
with  decay  or  fillings,  this  is  the  best  method  (Fig.  705). 

A  lateral  can  be  supported  in  like  manner  by  the  adjoining  central 
or  cuspid  in  accordance  with  any  of  the  methods  described.  As  a 
rule,  preference  should  be  given  the  cuspid  as  a  support  for  a  lateral, 
unless  the  condition  of  the  central  suggests  its  utilization  by  being 
pulpless,  or  its  appearance  suggests  that  an  artificial  crown  would  be 
an  improvement. 


350 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


The  replacement  of  a  superior  incisor  by  an  extension  bar  support 
from  a  bicuspid,  as  shown  in  Figs.  706  and  707  is  not  now  favoraby 
considered.  In  a  few  years  the  leverage  exerted  loosens  the  bicuspid. 
Preferably  place  an  open-face  cap  with  a  pin  or  pins  on  the  bicuspid, 
and  extend  a  narrow  iridio-platinum  bar  across  the  lingual  side  of  the 
cuspid  to  support  the  lateral  (Figs.  708  and  709),     The  cuspid  in  this 


Pig.  70s. 


Fig.  707. 


way  relieves  the  strain  on  the  bicuspid.     The  surface  of  the  enamel  of 

the  cuspid  can  be  cleaned  by  daily  passing  floss  silk  under  the  bar. 
The  method  of  construction  is  as  follows:  An  open-face  crown  is 

constructed  for  the  bicuspid  by  one  of  the  methods  already  described. 

The  crown  is  placed  on  the  tooth,  the  dummy  lateral  fitted  and  ce- 
mented in  position  with  sticky  wax,  an 
impression  taken  and ja  model  run  of 
investment  material.     The  model  will 


Pig.  708. 


Pig.  709. 


show  the  crown  and  lateral  in  position.  Place  a  narrow  strip  of 
platinum  plate,  gage  No.  38,  across  the  lingual  side  of  the  cuspid 
touching  the  gold  cap  and  backing  of  the  lateral.  Over  the  platinum 
place  a  still  narrower  piece  of  gold  clasp  plate,  about  gage  No.  28,  or  a 
piece  of  half  round  wire,  gage  No.  14,  wax  the  ends  to  the  crown  and 
lateral  and  hold  it  in  position  in  the  center  with  investing  material. 


FIXED  CROWN-  AND  BRIDGE-WORK 


351 


When  the  ends  of  platinum  and  plate  or  wire  have  been  attached  with 
solder  to  the  crown  and  lateral,  the  investing  material  should  be  re- 
moved from  the  center  and  the  solder  flowed  across  the  piece  forming 
the  bar.  This  makes  a  bar  with  a  surface  of  platinum  resting  against 
the  tooth.  In  finishing  it  should  be  reduced  in  width  as  much  as  re- 
quirements for  strength  will  permit. 


Fig.  710. 


Fig.   711. 


Centrals,  Laterals  and  Cuspids  Combined. — Two  laterals  supported 
by  two  central  crowns  are  shown  in  Figs.  710  and  711  and  in  position 
in  712.  Lugs  are  best  additionally  formed  on  the  laterals  to  rest  on 
the  cuspids.  When  approximal  crowns  are  united  to  support  bridge- 
work,  as  in  this  case,  a  free  space  should  be  preserved  at  the  cervices 
between  their  respective  collars  to  properly  admit  the  gum  septa. 


Fig.  712. 

Figs.  713  and  714  show  a  bridge  of  the  incisors  supported  by  two 
collar  crowns  on  the  cuspid  roots. 

Open-face  cap-crowns  may  also  be  used  in  a  case  suitable  for  their 
application.  Figs.  715,  716  and  717  illustrate  a  case  with  open-face 
cap-crowns  for  supports.     In  the  construction  the  best  method  is  to 


352 


CROWN-,  BRIDGE-,  ANDPO  RCELAIN-WORK 


form  and  fit  the  caps  or  crowns  to  the  cuspids,  remove  them  in  a 
plaster  impression  and  "bite,"  make  models  and  then  bridge  between 


/'i>. 
^     W 


f    h 


V\  < 


V3 


'"''I  I     I    I      j_j_^,|iiL.LIi.i.iniiiiimiii,iiiii|i|UlJ||||[| 


Pig.   717. 

the  crowns  with  the  incisors.     The  edges  of  the  collars  of  open-face 
crowns  should  be  leveled  and  burnished  close  to  the  teeth.     If  pro- 


FIXED  CROWN-  AND  BRIDGE-WORK 


353 


perly  done  in  a  case  when  only  the  edge  is  visible  in  laughing,  they 
will  resemble  cervical  gold  filHngs.  Inlays,  bars  or  lugs  extending 
from  the  cuspid  crowns  into  the  first  bicuspids  can  be  utilized  as  an 
additional  anchorage  should  the  occlusion  of  the  anterior  teeth 
indicate  it. 

Gutta-percha  alone  or  in  combination  with  zinc  oxyphosphate  is 
suggested  for  cementation  in  many  of  these  cases  (see  Part  III, 
Chapter  XXI). 


Fig.  718.  " 

In  the  method  shown  in  Figs.  718  and  719,  for  the  insertion  of  two 
centrals,  the  leverage  exerted  on  the  bicuspids  will  in  a  few  years  loosen 
them  in  their  sockets.  The  addition  of  lugs  placed  on  the  distal  sides 
of  the  centrals  resting  on  the  laterals  will,  in  a  measure,  relieve  the 
stress,  but  will  have  a  tendency  to  press  the  laterals  forward;  conse- 
quently the  method  is  one  not  at  present  favorably  considered. 


Fig.  719. 

Cuspids,  Bicuspids  and  Molars  Combined. — ^Figs.  720  and  721  show 
bridge-work  supported  by  a  cuspid  porcelain-faced  crown  and  a  molar 
gold  cap-crown.  If  the  cuspid  is  sound  and  contains  a  vital  pulp, 
its  vitality  should  be  preserved  and  either  an  all-gold,  an  open- 
face  cap-crown,  or  a  Carmichael  attachment,  be  applied  in  preference 
to  the  form  illustrated.     In  the  case  of  a  pulpless  cuspid  an  inlay  in- 

23 


354  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

serted  on  the  lingual  side  with  a  post  in  the  canal,  is  often  preferable  to 
applying  an  artificial  crown  as  illustrated. 


Fig.  722. 


Bicuspids  and  Molars  Combined.    Use  of  Partial  Cap.— fig.  722 

presents  a  bridge  on  the  mandible  from  the  first  bicuspid  to  the  second 


FIXED  CROWN-  AND  BRIDGE-WORK 


355 


molar.  The  inclination  of  the  teeth  toward  each  other  suggested  the 
construction  of  the  bridge  in  the  form  illustrated.  The  molar  is  entirely 
covered  with  a  gold  cap.  The  bicuspid  is  capped  only  on  the  occlusal 
third  (A).  A  pin  inserted  in  the  cap  .fitting  a  hole  drilled  in  the  sulcus 
of  the  bicuspid  secures  the  cap  in  position.  A  gold  inlay  extending 
across  the  sulcus  with  a  short  pin  in  the  mesial  end  might  be  used  in 
preference.  This  latter  method  is  very  suitable  in  a  case  where  the 
crown  of  the  bicuspid  is  long  and  the  root  sHghtly  exposed.  Molars 
in  a  similar  condition  may  be  capped  in  like  manner  for  bridge-work. 


Pig.  724. 


Pig.  723. 


Fig.  723  and  724  illustrate  a  bridge  supported  by  short  gold  caps  on 
both  bicuspid  and  molar.  The  caps  in  such  cases  may  be  swaged  or 
cast.     (See  Figs.  535  and  536.) 

Fig.  725  illustrates  a  case  of  bridge-work  supported  on  an  abraded 
bicuspid  and  molar  by  gold  partial  caps  or  tips  with  pins,  the  construc- 
tion of  which  is  described  in  Part  III,  Chapter  XVIII.  It  will  be 
noticed  that  the  molar  tips  forward  considerably.  The  use  of  this 
method  is  preferable  to  using  gold  crowns,  which  in  this  case  would 


Pig.  725. 

involve  extensive  trimming  and  probably  the  removal  of  the  pulps  of 
the  teeth. 

Fig.  726  represents  a  case  in  which  the  superior  third  molar  and  the 
first  bicuspid  are  utilized  for  the  attachment  of  a  bridge  to  support  the 
loss  of  the  intervening  teeth.  Fig.  727  represents  the  teeth  prepared 
for  the  bridge.  A,  the  Ungual  cusp  of  the  bicuspid  is  cut  down  to  allow 
the  placing  of  a  sufficiently  thick  cusp-cap;  B,  a  hole  between  the  cusps 
for  a  retaining  pin;  C,  the  third  molar  made  uniform  in  size  from  neck 
to  occlusal  surface,  the  Matter  having  been  su€iciently  trimmed  without 


356 


CROWN-,  BRIDGE;  AND  PORCELAIN-WORK 


removal  of  the  pulp;  D,  a  partial  cap  constructed  so  as  to  cover  every 
portion  of  the  bicuspid  except  its  buccal  surface,  the  edge  of  the  cap 


Fig.  726. 

passing  under  the  gum  margin;  E,  a  retaining  pin  adapted  to  the  open- 
ing B;  F,  the  gold  cap  for  the  molar. 


D-, 


Pig.  727. 

Fig.  728  represents  the  bridge  anchored  in  position  with  cement. 
As  the  gold  attachments  and  backings  are  out  of  sight,  the  appearance 
presented  is  natural.     There  is  this  fact  to  be  considered  in  regard  to 


Pig.  728. 

the  use  of  the  partial  caps;  many  patients  can  be  induced  to  consent  to 
their  employment  who  would  refuse  to  submit  to  more  radical  meas- 
ures, and  thus,  even  when  the  latter  would  be  advisable,  the  former 


FIXED  CROWN-  AND  BRIDGE-WORK 


357 


may  be  employed  as  a  compromise  or  even  as  a  temporary  expedient. 
Having  once  tested  the  advantages  of  a  well-fitting  bridge,  the  wearer 
is  more  likely  to  consent  at  some  future  time  to  a  more  suitable  form  of 
construction. 

Incisors,  Cuspids,  Bicuspids  and  Molars  Combined. — Figs.  729  and 
730  represent  a  piece  of  bridge-work  extending  from  a  central  incisor  to 


Fig.  729. 

a  molar.  In  such  a  case  the  best  method,  especially  the  one  most 
likely  to  prevent  misfit  from  warping,  is  to  construct  the  front  section, 
consisting  of  the  central,  lateral  and  cuspid  first,  then  form  the  molar 
cap,  fit  it  with  the  front  section  of  the  bridge  in  position  in  the  mouth, 
remove  in  plaster  impression  and  "bite,"  and  then  construct  the  bicuspid 


Pig.  730. 


Pig.  731- 


and  molar  dummies  between  the  cuspid  and  the  molar  crowns.  First 
solder  the  bicuspid  and  molar  dummies  together  to  avoid  warping  and 
then  unite  them  to  the  cuspid  and  molar  crowns.  In  a  bridge  of  this 
character,  an  open-face  cap  or  other  suitable  form  of  crown,  may  be 
used  for  the  cuspid  in  cases  where  the  natural  crown  is  intact. 


358 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Fig.  732. 


Fig.  733. 


Fig.  734. 


FIXED  CROWN-  AND  BRIDGE-WORK 


359 


Extensive   Application  of  Fixed  Crown-  and  Bridge-work.— The 

following  illustrations  show  cases  of  extremely  large  operations  in 
fixed  crown  and  bridge-work. 

Ill  the  case  illustrated  in  Figs.  731,  732  and  733,  crowns  on  a  second 
bicuspid,  a  pulpless  molar  and  the  roots  of  a  cuspid  and  lateral  con- 
stitute the  abutments. 

Figs.  734  and  735  illustrate  an  extensive  case  of  artificial  replacement 
by  crowning  and  bridging  operations.  Fig.  734  represents  the  case  as 
presented  for  treatment.  The  few  remaining  superior  and  inferior 
natural  teeth  had  no  corresponding  antagonists,  which  caused  the  inter- 
locking and  abnormal  occlusion  shown.  The  superior  right  bicuspid, 
the  left  central  and  the  left  cuspid  were  crowned,  the  bicuspid  being 


Fig.  735- 

shortened  and  the  cuspid  lengthened  in  the  operation.  The  intervening 
lateral  root  between  the  central  and  cuspid,  having  been  treated  and 
filled,  was  allowed  to  remain.  With  the  three  crowns  to  serve  as  abut- 
ments, the  intervening  spaces  were  bridged  with  artificial  teeth,  the 
extension  on  the  left  side  being  supported  by  a  narrow  saddle.  The 
spaces  between  the  inferior  cuspids  and  molars  on  both  sides  were 
bridged,  the  bicuspid  on  the  left  supporting  the  bridge  of  the  cuspid  as 
on  the  right ;  the  left  cuspid  was  crowned  and  the  incisal  edges  of  the 
incisors  trimmed  even.  Fig.  735  illustrates  the  finished  case  and  shows 
the  artificial  restoration  of  the  parts. ^ 

1  Fifteen  years  after  the  performance  of  this  work  by  Dr.  H.  A.  Parr,  the  case 
was  examined  by  the  author.  The  membranes  under  the  saddle  on  the  left  side 
had  settled,  leaving  a  space,  but  otherwise  the  work  seemed  to  be  in  fair  condition. 


36o 


CROWN;  BRIDGE-,  AND  PORCELAIN-WORK 


aimiiiiiiiiiiiiii;ii:niniiiim 
Fig.  736. 


Fig.  737. 


FIXED  CROWN-  AND  BRIDGE-WORK  361 

Figs.  736  and  737  represent  an  extensive  case  of  crown- and  bridge- 
work.  The  occlusal  surfaces  of  the  teeth  were  affected  with  abrasion. 
Gold  crowns  with  porcelain  facings  which  viewed  laterally  presented 
the  form  illustrated  in  outline  in  Fig.  736,  were  mounted  on  the  incisors 
and  cuspids,  the  pulps  of  which  were  preserved.  The  posterior  teeth 
were  crowned  with  all-gold  crowns.  The  missing  teeth,  except  those 
on  the  lower  left  side,  were  artificially  restored  with  bridge-work. 

Criticism. — Fixed  bridge-work  of  the  extensive  character  illustrated 
in  some  of  the  cases  shown  is  seldom  constructed  now,  for  reasons  which 
have  been  discussed  and  explained  in  Part  IV,  Chapter  XL  Remov- 
able forms  with  saddles  affording  alveolar  support  are  adopted  in  pref- 
erence. These  cases  are  therefore  presented  to  illustrate  what  has  been 
done  in  the  past  history  of  the  art,  and  not  as  methods  recommended  for 
practice  at  the  present  time. 


CHAPTER  XI 


SECTIONAL  AND  DETACHABLE  BRIDGE-WORK 


Pig.  738. 


CONSTRUCTION  IN  SECTIONS — -BAR  ATTACHMENT — DOVETAIL  LUG  AT- 
TACHMENT— DETACHABLE  DOUBLE-CAP  BICUSPID  AND  MOLAR 
CROWNS — DETACHABLE  GOLD  SEME-CIRCULAR  POST  CROWNS 

Construction  in  Sections. — The  construction  of  bridges,  especially- 
large  cases,  in  detachable  sections,  is  often  desirable  and  advantageous. 
This  is  owing  to  the  tilted  position  of  some  of  the  abut- 
ment teeth  or  roots  which,  in  a  case  of  bridge- work  extended 
to  both  sides  of  the  mouth,  renders  paralleling  of  their 
sides  extremely  difficult.  Also,  that  plan  is  to  be  considered 
when  the  condition  of  some  tooth  or  teeth  present,  in- 
cluded or  not  included  in  the  bridge,  as  for  instance  when 
affected  with  pyorrhea,  may  suggest  the  probable  necessity 
of  removal  of  the  cemented  bridge  in  the  future  for  altera- 
tion or  addition.  Removal  of  abutment  crowns  set  with  oxyphosphate 
is  usually  so  difficult  that  they  are  mutilated  or  destroyed.  In  such 
cases,  the  most  stable  section  or  sections  of  the  bridge — that  is,  the 
section  or  sections  least  liable  to  be  removed  should  be  made  first  and 
then  the  other  section  or  sections  formed  to 
connect  with  them.  This  is  accompHshed  by 
the  use  of  a  detachable  connecting  attach- 
ment or  anchorage. 

To  explain  such  construction  we  will  take 
the  case  shown  in  Fig.    729.     The   section 
from  the  molar  to  the  cuspid  can  be  made 
as  the  first  section,  and  the  central  and  lateral 
added,  with  a  lug  from  the  lateral  as  a  support- 
ing abutment  anchored  in  the  gold  forming        \    \  'I  \    \  :  i 
the  lingual  side  of  the  cuspid,  as  shown  in               ^^^ 
Fig.  738,  and  ready  for  insertion  in  Fig.  739.  , 
Any  required  removal  of  the  front  section  will  leave  the  remainder  of 
the  work  intact. 

Bar  Attachment.— This  form  cemented  to  position  with  amalgam 
has  the  advantage  over  the  use  of  an  inlay  in  that  removal  of  the  amal- 
gam will  loosen  the  bar  without  injury  to  the  anchorage  cavity,     it  is 

362 


739- 


SECTIONAL  AND  DETACHABLE  BRIDGE-WORK  363 

practically  applied  to  a  gold  bicuspid  or  molar  crown.     The  method  of 
construction  is  explained  in  Part  IV,  Chapter  IV. 

Dovetail  I/ug  Attachment. — In  this  method  the  attachment  is 
formed  on  the  outside  of  the  abutment  crown  in  contradistinction  to 
the  others  desciibed,  which  are  inserted  in  the  crown.     Fig.  740  il- 


FiG.   740. 

lustrates  a  case  of  this  kind.  The  teeth  forming  the  abutments  lean 
toward  each  other  distally  and  mesially  over  the  space  to  be  bridged, 
as  shown  on  the  original  model,  Fig.  741.  The  bridge  is  supported  by 
two  lugs  or  shoulders  on  the  abutment  crowns,  which  slide  into  the  slots 


Fig.   741. 

in  the  dummies  (Figs.  742  and  743).  These  supporting  shoulders  and 
slots  are  made  by  shaping  two  pieces  of  platinum  plate  to  the  form 
shown  in  Fig.  744,  so  that  one  will  telescope  the  other.  The  inner  one 
is  then  invested  on  the  outside  surface  and  the  inside  filled  in  with  gold 


Pig.  742. 


CD 


Fig.   743. 


Fig.  744. 


plate.  The  outer  piece  is  filled  inside  with  investing  material  and  gold 
plate  is  flowed  over  the  outside  surface.  The  inner  pieces  which 
form  the  shoulders  are  first  soldered  to  the  crowns  and  afterward  the 
outer  ones  forming  the  slots  are  adjusted  to  them  in  the  dummies 
and  soldered  in  position  in  the  bridge. 

Fig.  745  shows  a  bridge  constructed  with  an  attachment  similar  to 


364 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


that  just  described  at  one  end  and  a  double-cap  attachment  at  the 
other. ^     In  either  of  these  forms,  gutta-percha  can  be  used  to  attach 

the  bridge,  which  can  be  de- 
tached by  the  dentist  in  case  of 
need: 

A  pin  that  glides  into  a 
tube  placed  in  or  on  the  side  of 
the  crown   approximal  to  the 


Pig.  745. 


Fig.  746. 


bridge,  such  as  is  shown  in  Fig.  746,  can  be  utilized  instead  of  the 
attachment  described  in  the  above  cases. 


Fig.  747. 

Detachable  Double-cap  Bicuspid  and  Molar  Crowns. — Such  forms 
are  at  times  desirable  and  preferable  to  the  use  of  the  previously  de- 
scribed attachments,  to  permit  the  removal  of  a  retaining  cap  or  caps. 


Fig.  748. 

In  the  case  illustrated  in  Fig.  747  the  lines  of  the  sides  of  the  bi- 
cuspid and  molar  were  trimmed  parallel  or  only  slightly  tapering.  The 
natural  crowns  having  been  considerably  broken  down  by  decay 
were  shaped  up  with  amalgam.  Impressions  of  them  were  next  taken 
in  tubes  with  impression  compound  and  amalgam  dies  made.     On 

'  Case  of  Dr.  C.  L.  Alexander. 


SECTIONAL  AND  DETACHABLE  BRIDGE-WORK  365 

each  of  the  dies  a  close-fitting  cap  of  thin  platinum  about  gage  No.  38 
was  made  in  sections.  The  cap  was  first  swaged  on  a  fusible  metal 
die  made  from  the  amalgam  die,  and  transferred  to  the  latter  for  the 
final  shaping.     The  caps  were  fitted  in  the  mouth  and  a  plaster  im- 


FiG.   749. 

pression  taken,  removing  the  caps  in  position.  The  amalgam  dies  were 
then  inserted  in  the  caps  and  a  model  and  articulation  made,  with  the 
caps  on  their  dies  in  the  exact  relationship  they  will  hold  in  the  mouth, 
as  shown  in  Fig.  748. 


Fig.  750. 

Over  each  cap  a  second  cap  of  gold  was  made  which  did  not  extend 
to  the  gingival  margin  by  one-sixteenth  of  an  inch  (Fig.  749).  The 
dummy  or  bridge  teeth  were  then  constructed  between  the  caps,  as 
shown  in  Fig.  750. 


Fig.  751. 

The  platinum  caps  were  first  cemented  with  oxyphosphate  on  the 
teeth.  When  it  had  set  the  gold  crowns  were  cemented  with  gutta- 
percha cement  over  the  platinum  tooth-caps,  from  which  they  may 


366  CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 

be  detached  at  any  time.^  The  thin  platinum  caps  appKed  as  de- 
scribed were  quickly  and  easily  constructed.  Where  erosion  is  active  and 
pyorrhea  present,  as  in  this  case,  they  can  be  extended  far  under  the 
gum  margin  to  protect  the  dentin  of  the  root  without  producing  irri- 
tation, if  the  platinum  is  tapered  to  a  feather  edge  and  closely  fitted 
and  burnished  to  the  surface  of  the  root. 

Detachable  Gold  Semi-circular  Post  Crowns. — The  use  of  detach- 
able gold  abutment  crowns  cemented  with  gutta-percha  is  a  method 
that  permits  removal  of  the  bridge  very  easily,  and  is  especially  applica- 


F  G.  752.  Pig.  753. 

ble  to  cases  of  pyorrhea  requiring  periodical  treatment  that  suggest 
the  temporary  removal  of  the  bridge  for  the  purpose. 

Fig.  751  shows  a  lower  case  with  a  sectional  bridge.  In  this  case 
the  roots  are  trimmed  to  within  about  one-eighth  of  an  inch  of  the 
gingival  margins  and  gold  collar  caps  with  posts  are  fitted  to  ach. 
Solid  all-gold  crowns  are  made  for  the  molars  and  crowns  with  porce- 
lain facings  for  the  cuspids  and  first  bicuspids.  To  each  crown  is 
fitted  a  large  half-round  or  oval-shaped  post  attached  to  the  cap, 
A,  B  and  C,  Fig.  752,  show  their  construction  in  section.  The  teeth 
were  reproduced  in  three  separate  bridges,  as  shown  at  A,  B  and  C, 
Fig.  753- 

^  This  case  was  constructed  in  this  manner  by  the  author,  for  the  reason  that 
the  remainder  of  the  teeth  were  being  rapidly  shortened  by  mechanical  abrasion, 
and  the  intention  is  to  open  the  "bite"  later  on  and  protect  the  other  occluding 
surfaces.  When  this  is  done,  the  occluding  surfaces  of  the  bridge  can  be  proportion- 
ately increased  in  thickness.  A  detachable  form  of  construction  was  considered 
advisable  for  the  reason  also  that  the  patient  exercised  such  an  unusual  amount  of 
force  in  occlusion,  that  repair  or  restoration  of  occluding  surfaces  was  liable  to  become 
necessary  at  times. 


CHAPTER  XII 

THE  HYGIENIC  CONDITION  OF  THE  MOUTH  AS  AFFECTED  BY  FIXED 

BRIDGE-WORK 

CONSIDERATION  OF  THE  SUBJECT — REQUIREMENTS — METHOD  TOR  CLEAN- 
LINESS AND  HEALTH 

Consideration  of  the  Subject. — The  probable  future  condition  of 
the  mouth  in  which  a  piece  of  bridge-work  is  permanently  cemented  is 
a  matter  of  the  deepest  interest  to  both  patient  and  operator.  There 
is  no  valid  reason  why  an  artificial  structure  in  the  mouth  should  be 
more  hurtful  than  the  natural  teeth,  provided  that  correct  conditions 
are  observed  in  its  construction,  and  proper  measures  are  taken  for 
their  maintenance.  Collars  imperfectly  fitted  at  the  cervix  cause  in- 
flammation of  the  gingival  margin  and  permit  infection  of  the  cement 
under  them,  which  contributes  additionally  to  the  inflammation.  In 
pulpless  teeth  this  infection  in  the  cement  penetrates  the  dentin,  in 
time  reaches  the  pulp-canal  and  finally  the  apex  of  the  root.  This  is 
one  of  the  reasons  why  the  apices  of  roots  the  canals  of  which  have 
been  properly  treated  and  filled  show  areas  of  focal  infection.  The 
natural  teeth  demand  care  on  the  part  of  their  owners,  and  equally 
or  more  so  do  all  forms  of  artificial  dentures  require  attention  to  secure 
their  cleanliness  and  thus  preserve  the  health  of  the  adjacent  tissues. 
The  result  of  wearing  a  piece  of  fixed  bridge-work  is  entirely  depend- 
ent, in  the  first  place,  on  the  proper  apphcation  of  principles  and  skill 
in  every  detail  of  construction  of  both  crowns  and  bridge;  and  in  the 
second  place,  upon  the  maintenance  of  cleanhness.  Neglect  of  a  single 
requirement  will  so  far  detract  from  the  usefulness  of  the  work,  that 
it  may  influence  the  final  result  disastrously. 

Requirements. — Firm,  properly  selected  abutments  will  not  redeem 
incorrect  conception  or  faulty  construction;  neither  will  the  best  con- 
struction remedy  that  which  is  wrong  in  principle  or  application.  Self- 
cleansing  spaces,  if  improperly  formed,  have  exactly  the  contrary  effect 
from  what  is  intended,  by  becoming  receptacles  for  particles  of  food 
debris,  instead  of  preventing  their  accumulation. 

Inaccessible  spaces  or  interstices,  which  are  apt  to  cause  uncleanli- 
ness,  should  be  avoided.  Continuity  of  structure  of  the  several  parts  of 
crowns  and  bridges  is  essential  to  fully  insure  a  perfect  hygienic  condition. 

Methods  of  Cleanliness  and  Health. — The  health  of  a  mouth  con- 
taining a  piece  of  bridge-work  constructed  under  these  precautions  can 
be  readily  maintained.  For  this  purpose  a  suitably  formed  tooth-brush 
and  properly  shaped  bristle  points  in  a  porte  carrier,  which  will  reach 
places  not  cleaned  by  the  tooth-brush,  and  a  dentifrice,  are  necessary. 

367 


368  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Floss  silk  charged  with  tooth-powder  or  paste  can  be  passed  through 
interstices  between  the  necks  of  the  crowns  by  the  aid  of  a  slightly- 
curved  blunt-pointed  needle  and  drawn  along  the  gum  under  the  bridge 
to  remove  accumulation  of  debris  otherwise  inaccessible.  A  solution 
of  detergent  mouth-lotion  or  disinfectant  in  water,  injected  with  a 
dental  syringe,  can  be  used  advantageously  to  wash  out  such  places 
and  maintain  a  healthy  condition  of  the  gums.  The  prophylactic 
measures, 'as  outlined,  should  be  practiced  at  least  once  or  twice  daily;  if 
only  once,  preferably  before  retiring.  In  addition  to  the  above,  bridge- 
work  should  be  thoroughly  cleansed  by  the  dentist  at  regular  intervals. 

So  cared  for,  a  fixed  bridge  will  not  militate  against  the  absolute 
wholesomeness  of  the  mouth;  but  it  can  hardly  be  expected  that  the 
insertion  of  bridge-work  will  insure  a  state  of  the  mouth  which  for 
cleanliness  will  be  superior  to  the  presence  of  the  natural  teeth.  Neg- 
lect on  the  part  of  the  patient  to  perform  such  duties  as  are  necessary 
to  preserve  the  natural  teeth  in  a  healthy  state  wiU  have  about  the 
same  or  worse  effect  on  an  artificial  denture.  The  attention  required 
to  be  given  to  bridge-work  is  not  greater  than  is  commensurate  with 
the  advantages  which  it  confers  on  the  wearer. 

To  offset  the  objections  used  against  fixed  bridge-work  regarding 
hygiene  in  this  era  of  oral  prophylaxis,  many  practitioners  favor  the  re- 
movable form.  So  constructed,  the  patient  is  able  to  remove,  cleanse 
and  replace  the  denture.  This  certainly  is  advantageous  in  an  ex- 
tensive piece  of  bridge-work.  In  the  use  of  small  cemented  bridges 
towards  the  front  of  the  mouth,  involving  the  use  of  not  more  than  two 
abutments,  if  the  work  is  properly  constructed,  especially  respecting 
interproximal  spaces  and  continuity  of  structure,  the  comparison  is 
modified,  as  no  appreciable  advantage  is  gained  by  making  it  remov- 
able. The  two  crowns  that  constitute  the  abutments,  if  they  stood 
alone,  would  not  be  classed  as  insanitary,  if  properly  constructed  and 
united  to  the  roots  or  teeth  with  an  antiseptic  cement;  why  then, 
should  the  cemented  abutments  of  an  unremovable  bridge  be  so  con- 
sidered? The  dummy  teeth  that  intervene  between  the  abutments 
and  lock  in  particles  of  food  with  the  secretions  constitute  the  objec- 
tionable factor.  Cleaning  the  surfaces  and  interstices  of  such  a  bridge 
in  the  front  of  the  mouth  can  be  effectively  performed  by  proper  means, 
but  not  so  easily  as  when  removable. 

An  unclean  condition  of  properly  constructed  fixed  bridge-work  is 
frequently  attributable  more  to  the  fact  that  patients  were  not  informed 
as  to  just  how  to  take  care  of  it,  or  did  not  possess  the  necessary  means 
to  carry  out  that  care  than  to  neglect  on  their  part.  In  the  former 
event  the  practitioner  is  at  fault  in  having  failed  to  properly  instruct 
the  patient  and  prescribe  the  needed  care. 


PART  V 
REMOVABLE  BRIDGE-WORK 


CHAPTER  I 

REMOVABLE  BRIDGE-WORK 

Limitations — requirements — examination  models — forms  of 
crowns,  attachments  and  supports — removable  retaining 
abutments — removable  supporting  abutments — the  tube 
and  split-post  attachment — construction  of  the  split  post — 
split-post  swaging  device — split-post  burnisher — tele- 
scope crowns — the  outer  or  telescoping  cap — contour — 
the  cusp-cap — telescope  crown  with  tube  and  split  post — 
removal  of  the  cap  from  the  die — tube  and  split-post  an- 
terior crowns — incisors,  cuspids  and  bicuspids  avith  porce- 
LAIN FACINGS — ^THE  OUTER  CAP — CONVERGING  TEETH  AND  ROOTS 
— RETAINING  INLAY  ABUTMENTS — ^BICUSPIDS  AND  MOLARS — THE 
MATRIX  OR  FEMALE  INLAY — SPLIT  POST  AND  SUPPLEMENTARY  OR 
MALE  INLAY — ^A  PIN  BENDER — VARIATIONS  IN  METHOD — INCISORS 
AND  CUSPIDS — ^TO  TAKE  THE  IMPRESSION — INSERTION  OF  THE 
SPLIT  POST — THE  SUPPLEMENTARY  INLAY — USE  OF  SWAGED  FIRST 
OR  FEMALE  MATRIX — SUPPORTING  ABUTMENTS — SPECIAL  FORMS 
OF  ATTACHMENTS — COLLAR  AND  PARTIAL  CAP — FLANGED  COLLAR 
ATTACHMENT — LUG  COLLAR  SUPPORT — SPLIT-BAR  ATTACHMENT — 
CONSTRUCTION — THE  SPLIT  BAR — THE  BOX — PARALLELING  THE  BOX 
— THE  SHIELD — WINGED  LUG  ATTACHMENT — ^DOVE-TAIL  FLANGE 
AND  SPLIT-POST  ATTACHMENT — SOLID  PIN  AND  TUBE  ATTACHMENT — 
COMPARATIVE  VALUES  OF  THE  SEVERAL  FORMS  OF  ATTACHMENTS — 
RETENTIVE  ATTACHMENTS — RETENTIVE  INLAY  ATTACHMENTS — 
SUPPORTING  ATTACHMENTS 

The  evident  advantages  of  bridge-work  early  stimulated  the  in- 
ventive genius  of  dental  mechanists  to  improve  the  methods  and  forms 
of  its  construction  and  extend  its  application.  With  these  objects  in 
view,  methods  have  been  introduced  by  which  bridges  are  so  constructed 
as  to  be  removable  and  replaceable  by  the  patient.  The  importance  of 
oral  hygiene  is  now  generally  recognized,  and  the  use  of  fixed  bridge- 
work,  as  it  cannot  be  removed  for  the  purpose  of  cleansing,  is  criti- 
cised and  by  some  entirely  condemned.  As  a  result,  the  subject  of 
removable  bridge-work  is  being  more  actively  discussed  than  formerly, 
its  construction  studied  and  more  generally  adopted.  Its  use  over- 
comes the  chief  objections  urged  against  the  system. 

371 


372  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Limitations. — ^Large  bridges  are  usually  much  more  easily  made  in 
a  removable  form  than  small  pieces,  which  in  contradistinction  present 
some  of  the  best  features  of  the  permanently  attached  methods.  Many 
of  the  smaller  bridges  cannot  be  made  removable  as  practically  as  the 
larger  ones.  In  a  large  proportion  of  cases  where  properly  constructed 
fixed  bridge-work  is  applied,  the  removable  feature  would  be  of  no 
material  benefit  as  far  as  regards  the  health  of  the  abutments  or  of  the 
adjoining  teeth;  neither  would  it  be  of  any  great  advantage  regarding 
cleanliness.  These  reasons,  together  with  the  fact  that  removable 
bridge- work  is  most  intricate  and  laborious  in  construction,  largely 
combine  to  restrict  its  use  to  large  bridges  or  those  requiring  saddles, 
and  the  form  termed  removable  plate  bridge-work,  which  imperatively 
demands  removal  for  cleanliness  and  health  of  the  membrane  on  which 
it  rests. 

Requirements. — In  the  construction  of  removable  bridge-work  the 
prime  requisite  is  that  the  posts  and  collars,  or  other  form  of  attach- 
ments used,  shall  be  so  constructed  that  the  denture  will  move  evenly 
on  and  off  the  supporting  capped  roots  or  crowns  in  adjustment  and 
removal.  To  secure  this,  removable  attachments  and  gold  crowns 
must  be  so  shaped  that  the  lines  of  the  different  parts  are  parallel  to 
one  another.  This  is  absolutely  necessary,  if  the  denture  extends  to 
both  sides  of  the  arch,  as  otherwise  the  stabiHty  of  abutment  roots  and 
crowns  would  be  impaired,  and  in  time  irreparably  destroyed  by  daily 
removal  and  insertion  of  the  denture. 

Examination  Models.— Two  wax  or  compound  impressions  and 
"bites"  should  be  first  taken,  that  will  include  all  the  teeth  in  each  jaw, 
then  plaster  models  made  and  mounted  on  articulators.  One  of  these 
models  is  for  the  purpose  of  studying  the  case  outside  of  the  mouth 
and  the  preparation  of  the  abutments,  the  other  is  to  refer  to  later  on. 
The  most  advisable  method  may  be  determined  more  easily  by  the 
aid  of  a  model  than  in  the  mouth. 

Forms  of  Crowns,  Attachments  and  Supports 

In  removable  bridge- work  two  classes  of  abutments  are  used:  Re- 
taining and  Supporting. 

Removable  Retaining  Abutmients. — These  forms  hold  the  bridge 
firmly  in  position  in  the  mouth,  preventing  its  dropping  or  shifting. 
Split-post  and  tube  collars,  telescope  crowns,  inlay  and  split-post 
abutments,  or  any  devised  abutments  that  firmly  retain  a  bridge  are 
Retaining  Abutments. 

Removable  Supporting  Abutments. — These  are  such  forms  as  sup- 
port an  end  or  any  part  of  a  bridge,  but  do  not  retain  it  in  position.     A 


REMOVABLE  BRIDGE-WORK 


373 


countersunk  inlay  or  gold  filling  in  which  a  lug  rests  or  anchors,  or  any 
contrivance  designed  to  support,  but  not  retain  a  bridge,  is  a  Supporting 
Abutment. 

A  knowledge  of  and  practical  experience  in  the  formation  of  remov- 
able bridge  abutments  should  first  be  acquired  before  commencing  the 
construction  of  practical  work.  Accordingly,  the  constructive  details 
of  Retaining  and  Supporting  Abutments,  such  as  are  used  in  the  Peeso^ 
and  similar  styles  of  bridges,  will  be  given  first  so  that  they  can  be 
preliminarily  practiced  by  the  construction  of  one  or  more  specimens. 
The  Tube  and  Split-post  Attachment. ^ — This  is  the  most  used  re- 
tentive abutment. 

The  tube  is  made  on  a  small  steel  mandrel. 
These  mandrels  are  termed  "Tube  Mandrels" 
and  are  of  six  sizes,  Nos.  i,  2,  3,  4,  5,  and  6 


3      4     5 


± 


Ul 


'_*, 


Pig.  754- 


Fig.  756. 


(Peeso),  closely  corresponding  to  Nos.  48,  49,  50,  51,  52,  and  53,  twist 
drill  and  steel  wire  gage  (B.  &  S.),  as  shown  in  Fig.  754.  The  tube  is 
made  of  ten  per  cent,  iridio-platinum  plate  gage  No.  32. 

As  the  tube  when  finished  will  be  one  or  two  sizes  larger  than  the 
mandrel  on  which  its  shaping  is  started,  calculation  should  be  made 
accordingly  in  selecting  the  size  of  the  mandrel.  A  canal,  for  instance, 
that  will  receive  a  tube  on  a  No.  4  mandrel  requires  mandrels  Nos. 
2  and  3  for  shaping  and  No.  4  for  finishing. 

To  systematize  the  subject  of  the  size  of  tubes  in  their  application 
to  canals,  the  tube  is  given  the  number  of  the  size  of  the  last  mandrel 
it  was  swaged  on  or  the  one  over  which  it  fits  tightly.  So  regulated 
in  size,  Nos.  i  and  2  tubes  are  used  in  small  roots,  such  as  the  superior 
laterals  and  bicuspids,  Nos.  2  and  3  in  superior  central  incisors,  Nos.  3 
and  4  in  large  superior  centrals  and  in  both  superior  and  inferior 
bicuspids  and  Nos.  5  and  6  in  superior  and  inferior  molars. 

1  So  termed,  as  Dr.  F.  A.  Peeso's  systematic  constructive  details  have  contributed 
so  much  to  improving  the  art. 

2  Iridio-platinum  hollow  wire  is  considerably  used  for  tubes  of  late  in  preference 
to  making  them.     Ready-made  tubes  with  split  posts  are  also  manufactured. 


374 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


A  piece  of  plate  seven-sixteenths  of  an  inch  wide  is  cut  in  the  direction 
the  metal  has  been  rolled,  perfectly  square  on  the  end  and  beveled  to  a 
knife  edge  (Fig.  755).  Anneal  the  plate,  dip  it  in  acid  and  wash  and 
dry  perfectly.  Turn  the  edge  of  the  platinum  evenly  at  an  angle,  as 
shown  in  Fig.  756.  This  is  best  done  by  seizing  the  edge  in  a  hammer- 
headed  hand-vise  with  seven-eighths-inch  jaws,  the  serrations  of  the 
jaws  having  been  removed  and  the  edge  of  one  of  them  rounded  (A, 
Fig.  757),  and  bending  the  platinum  over  the  rounded  edge  (B).  The 
platinum  is  laid  on  the  surface  of  a  flat  anvil,  the  mandrel  selected  for 
starting  is  placed  in  the  fold  of  the  platinum,  the  shank  of  the  mandrel 
being  held  by  a  pin  vise,  and  the  edge  of  the  platinum  gradually  turned 


Pig.  757. 


Pig.  759. 


over  with  a  fine  flat  file  to  meet  the  surface  of  the  platinum  strip,  as 
shown  in  Fig.  758.  The  mandrel  can  be  slightly  rolled  in  the  operation 
to  bring  the  edge  against  the  surface  of  the  plate  (Fig.  759),  but  it 
must  not  be  rolled  beyond  that  point,  as  that  would  double  the  plate, 
as  shown  in  Fig.  760.  The  mandrel  is  removed,  a  very  small  piece  of 
pure  gold  is  placed  in  the  seam  and  the  tube  is  held  in  a  Bunsen  flame 
(Fig.  761).  When  a  sufficient  degree  of  heat  is  reached,  the  gold  will 
flow  along  the  seam  and  form  a  joint  without  obstructing  the  passage 
of  the  mandrel  inside.  If  it  does  obstruct,  too  much  gold  has  been 
used.  Heating  the  tube  to  a  high  heat  may  correct  this  by  diffusing 
the  gold  through  the  platinum.  If  not,  a  new  tube  must  be  formed. 
The  next  size  larger  mandrel  is  then  forced  through  the  tube  to 


REMOVABLE  BRIDGE-WORK 


375 


stretch  the  metal  and  smooth  the  inside.  This  is  best  accomphshed 
by  placing  the  end  of  the  tube  against  the  surface  of  an  anvil,  and  tap- 
ping the  mandrel  through,  as  shown  in  Fig.  762.  The^  tube  is  then 
annealed  and  enlarged  to  the  size  of  the  next  larger  mandrel.  The 
surplus  metal  is  removed  with  shears,  resting  the  flat  side  of  one  of  the 
blades  against  the  surface  of  the  metal.  The  joint  is  trimmed  even 
with  the  rest  of  the  tube  with  a  fine  flat  file.  Should  the  tube  fit  the 
mandrel  so  tightly  as  to  be  diflicult  to  remove,  roll  the  tube  and  man- 
drel under  a  dull,  smooth  flat  file,  to  shghtly  stretch  the  tube.  To  close 
the  end  of  the  tube  trim  the  metal  even,  slightly  burnish  in  the  edge 
(Fig.  763),  and  over  the  opening  solder  a  piece  of  metal  of 
the  same  gage  as  the  tube.  This  is  most  easily  done  by 
placing  a  small  piece  of  the  platinum  on  a  charcoal  block, 
melting  a  particle  of  pure  gold  on   its   surface,  and   then 


fT^ 


Fig.  760. 


Fig.  761. 


Fig.  762. 


Pig.  763. 


placing  the  end  of  the  tube  against  it  and  again  fusing  the  gold,  as 
shown  in  Fig.  764.  The  surplus  plate  is  then  removed  and  the  part 
finished  with  a  fine  file. 

The  point  of  the  mandrel  selected  as  the  size  for  the  tube  is  inserted 
in  the  orifice  of  the  tube,  its  closed  end  placed  on  a  block  of  lead,  and 
the  mandrel  driven  into  the  tube,  giving  it  the  exact  dimensions  and 
the  end  a  slightly  coned  form. 

Construction  of  the  Split  Post. — The  post  is  made  of  half-round 
platinized  gold  wire  (gold  clasp  metal),  gage  No.  12  to  15,  and  when 
doubled   about   one-fourth   inch   longer   than    the   tube.     The   most 


376 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


convenient  way  is  to  use  a  long  piece  of  wire  and  double  one  end  of  it 
for  a  post  as  required.  The  gage  of  the  wire  when  doubled  should  be 
slightly  greater  than  the  diameter  of  the  hole  in  the  tube.  The  average 
is  gage  Nos,  14  for  No.  i  and  2  tubes;  gage  No.  13  for  Nos.  3  and  4, 
and  gage  No.  12  for  No.  5  and  6.  The  sharp  edge  of  the  wire  should 
be  rounded  so  that  the  finished  post  will  have  a  very  small  seam  on  each 
side  that  will  indicate  and  easily  permit  the  introduction  of  a  thin  knife 
blade  to  effect  expansion,  as  shown  at  A  and  B,  Fig.  765.  The  required 
length  of  wire  is  bent  about  one-eighth  of  an  inch  from  the  center  and 
the  flat  side  of  the  shorter  end  brought  against  the  side  of  the  other 
so  that  the  longer  end  extends  as  shown  in  Fig,  766.  The  wire  should 
be  well  annealed  before  being  bent,  and  each  time  between  the  bendings. 


Fig.  765.  Fig.  767. 


Fig.  764. 


Fig.  768. 


When  the  shorter  end  of  the  wire  meets  the  longer  one,  the  flat  sides  are 
brought  together,  as  shown  in  Fig.  767,  and  so  held  by  a  soldering 
clamp  and  heated  to  a  red  heat,  then  plunged  into  water.  This  sets 
the  portions  of  the  metal  brought  together  in  close  contact,  in  which 
position  they  remain  while  being  soldered.  The  loop  portion  is  next 
held  by  a  clamp  and  the  ends  united  by  the  least  possible  quantity  of 
coin  gold,  using  the  long  end  of  the  wire  as  a  shelf  to  hold  the  solder, 
as  seen  at  A,  Fig.  768.  The  ends  connected  in  this  way  leave  the  loop 
section  to  form  the  spHt-pin  post.  The  extending  end  of  the  wire  is 
grasped  in  a  pin  vise  and  the  loop  portion  hammered  together  first  on 
the  face,  and  then  in.  the  groove  of  an  anvil.  Between  the  blows  of  the 
hammer  the  post  must  be  rotated  so  that  the  two  sides  will  be  forged 
round  as  they  come  in  contact  (Fig.  769).  As  a  safeguard  against 
invasion  of  the  solder  in  the  seam  of  a  spHt  post  in  any  of  the  subsequent 
soldering  operations,  rouge  or  a  very  thin  film  of  mica  may  be  placed  to 


REMOVABLE  BRIDGE-WORK 


377 


remain  in  the  seam  between  the  two  halves  of  the  wire  before  they  are 
brought  together. 

The  wire,  still  grasped  in  the  pin  vise  is  next  trimmed  uniformly 
round  with  a  flat  file.  The  fit  of  the  wire  to  the  tube  should  be  tested 
frequently  by  placing  the  orifice  of  the  tube  over  the  point.  When  the 
post  begins  to  approach  the  required  size,  it  is  mounted  in  a  true-run- 
ning chuck  on  a  lathe,  and  further  uniformly  reduced  with  a  very  fine 
flat  file,  the  serrations  of  which  are  worn  smooth,  applied  lightly  against 
its  surface  with  the  smooth  surface  of  a  burnishing  file  against  the  other. 
When  the  post  nearly  enters  the  tube,  it  may  be  further  sufficiently 


Pig.   769. 


reduced  with  fine  emery  cloth  applied  on  a  flat  stick.  The  post,  having 
been  reduced  to  very  tightly  fit  the  tube,  is  "then  burnished  by  passing 
a  burnisher  lengthwise  over  its  surface  to  remove  the  fine  scratches  of 
the  emery  cloth,  and  give  it  a  uniformly  smooth  polished  surface. 
This  generally  permits  the  post  to  freely  enter,  if  not,  it  must  be  further 
reduced  and  again  burnished.  The  post  should  enter  and  move  in  the 
tube  uniformly  the  entire  length,  and  require  but  a  moderate  amount 
of  force  to  insert  or  remove  it. 

The  use  of  a  spHt  post  with  a  closed  point,  is  confined  to  a  long  tube 
and  where  the  post  when  removed  from  the  tube  will  be  so  exposed 
that  the  slit  can  be  easily  reached  and  expanded.  The  open  end  split 
post  is  the  best  form  to  apply  in  short  tubes  and  in  all-gold  bicuspid 


378 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


and  molar  telescope  crowns,  as  in  the  latter  the  slit  at  the  end  of  the 
post  is  more  easily  reached  than  on  the  side. 

When  the  end  of  a  split  post  is  being  removed  sufficiently  to  slightly 

expose  the  slit  (Fig.  770),  the  move- 
ment of  the  file  or  stone  should  be 
directed  in  the  line  of  the  slit,  to 
avoid  springing  the  sides  of  the  post 
apart  as  the  slit  is  reached. 

Split-post  Swaging  Device. — Fig. 
771  illustrates  the  Weinstein  swaging 
block  for  shaping  split  posts  by 
swaging.  The  groove  on  the  top  of 
the  block  is  to  be  used  in  hammering 
the  half  round  wire  when  it  is 
brought  together  to  form  the  post. 
The  ends  of  the  two  wires  having 
been  united  with  solder,  the  soldered 
end  is  seized  with  a  pin  vise;  the 
post  is  then  placed  in  one  of  the  grooves  in  the  center  of  the  block, 
two  sizes  larger  than  the  required  size  for  the  finished  post,  and  swaged 
between  the  two  sections  of  the  swager,  twisting  the  post  in  the  groove 


Fig.  770. 


Fig.  771. 


Fig.   772. 


between  the  blows  of  the  hammer.  The  post  is  then  transferred  to  the 
next  smaller  hole  and  again  swaged.  This  swaging  process  is  continued 
until  the  post  is  uniformly  reduced  to  a  suitable  size. 


REMOVABLE  BRIDGE-WORK 


379 


Split-post  Burnisher. — Fig.  772  illustrates  the  Weinstein  burnisher. 
The  post  is  placed  in  a  revolving  chuck  of  a  lathe,  the  burnishing  tool 
is  opened,  the  post  placed  in  the  grooved  side  and  the  smooth  side 
closed  gently  on  the  post.  The  chuck  is  then  revolved  and  the  post 
burnished  by  its  revolutions  against  the  burnished  steel.  The  tool  is 
gradually  clamped  together  tighter  on  the  post  as  the  burnishing 
progresses. 

The  use  of  tubes  and  spht  posts  is  much  facilitated  by  having  on 
hand  a  number  of  different  sizes  ready-made.  The  most  suitable  size 
can  then  be  immediately  selected.  These  posts  may  be  formed  at  a 
convenient  time,  or  by  an  assistant. 


Telescope  Crowns 

This  is  the  form  generally  preferred  for  gold  bicuspid  and  molar 
crowns  in  removable  bridge- work.  When  used  as  a  supporting  abutment 
they  are  made  without  a  post;  as  a  retaining  abutment,  with  a  post. 

The  sides  of  the  natural  crown  are  trimmed  as  for  an  ordinary  gold 
crown,  but  given  a  slightly  more  conical  form.  The  occlusal  section 
requires  to  be  removed  enough  to  allow  for  the  thickness  of  not  only 


Pig.  773. 


Fig.   774. 


Fig.  775.  Fig.  776. 


the  inner,  but  also  the  outer  cap  (Fig.  773).  Gold  coin  or  a  corre- 
spondingly hard  gold  plate,  which  will  not  stretch  in  wear,  is  absolutely 
necessary,  especially  for  the  outer  telescope  crown. 

The  collar  is  made  of  gold,  gage  No.  30,  cut  with  a  very  slight  flare 
toward  the  cervical  edge,  as  indicated  in  Fig.  774.  The  joint  is  sweated, 
or  united  with  hard  solder.  The  collar  is  fitted  closely  to  the  cervix  of 
the  tooth  and  uniformly  extended  well  under  the  gum.  The  sides  and 
occlusal  end  of  the  collar  should  be  given  the  same  curve  as  the  cervical 
section,  so  that  the  outer  collar  shall  fit  and  move  uniformly  over  it 

(Fig.  775)- 

The  edge  of  the  occlusal  end  of  the  collar  is  trimmed  off  enough  to 
leave  room  for  the  floor  and  a  thick  cusp-cap.     The  extreme  occlusal 


38o 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


edge  of  the  collar  is  turned  inward  with  small  pointed  pliers  so  as  to  give 
it  a  rounded  form,  as  shown  in  Fig.  776.  This  is  for  the  purpose  of 
permitting  a  slightly  rounded  edge  to  be  given  to  the  occlusal  end  of  the 
cap.  This  rounded  edge  is  to  facilitate  the  adjustment  of  the  collar 
of  the  finished  outer  crown  by  allowing  it  to  more  easily  slip  to  place, 
especially  should  it  be  inserted  a  trifle  out  of  line.. 

The  rounded  edge  of  the  collar  is  filed  level  so  that  all  parts  are  in  the 
same  plane.  The  floor  is  made  of  the  same  gold  as  the  collar,  gage 
No.  28,  cut  to  the  required  size.  The  plate  is  made  perfectly  flat  by 
swaging  in  the  Peeso  swaging  device.  Fig.  777,  The  plate  is  annealed, 
dipped  in  acid,  washed  and  sweated  or  soldered  to  the  collar.     The  edge 


Pig.  777- 

of  the  surplus  gold  is  cut  and  ground  level  with  the  sides  of  the  collar 
and  polished  (Fig.  778). 

The  Outer  or  Telescoping  Cap. — The  inside  of  the  inner  cap  is 
varnished,  a  strip  of  paper  is  wound  closely  around  it  and  secured  with 
a  wire  or  rubber  band  (Fig.  779).  Fusible  metal  that  melts  below 
212°  F.  is  then  poured  into  the  paper  Lube  (see  "Casting  the  Die," 
Part  I,  Chapter  V).  This  practically  makes  the  gold  cap  a  die  on 
which  to  form  the  outer  cap.  The  fusible  metal  is  later  removed  by 
immersion  in  boiling  water. 

The  measure  of  the  circumference  of  the  outer  collar  is  taken  at 
about  the  middle  line  of  the  inner  cap,  a  little  towards  the  occlusal  end, 
as  indicated  at  A,  Fig.  780.     The  gold  is  cut  with  a  slight  flare  as  for  the 


REMO  VA BLE  BRIDGE-WORK 


381 


inner  cap.  The  joint  of  the  collar  is  made  with  a  slight  overlap.  The 
collar  is  slipped  over  the  horn  of  the  anvil,  the  joint  hammered  and  then 
filed  level.  The  collar  is  annealed  and  placed  on  the  inner  cap-die  and 
pressed  down  with  the  finger  as  far  as  it  will  go.  The  occlusal  edge  of 
the  collar,  which  must  be  level,  is  placed  on  the  flat  surface  of  the  anvil 
and  the  die  is  hammered  into  it  to  position  (Fig.  781).  If  difficulty  is 
experienced  in  the  removal  of  the  collar  from  the  inner  cap,  burnish 
with  a  plate  burnisher  on  the  sides  in  a  circular  direction  around  the 
collar,  especially  toward  the  cervical  section;  wind  a  piece  of  cloth 


Fig.  778. 


Fig.  780. 


Pig.  779. 


Fig.  782. 


Pig.  781. 


around  the  collar,  then  seize  and  remove  with  the  fingers.  The  collar 
is  replaced  on  the  inner  cap,  the  cervical  edge  is  marked  and  trimmed  off 
to  about  one-sixteenth  of  an  inch  short  of  the  line  of  the  gum  margin 
of  the  inner  collar,  as  shown  in  Fig.  782.  The  occlusal  edge  of  the 
outer  collar  is  trimmed  a  trifle  flush  with  the  surface  of  the  floor  of  the 
inner  cap,  the  edge  is  pressed  inward  with  a  flat  file  and  then  filed  per- 
fectly level  with  the  surface  of  the  floor.  The  collar  is  removed  and  a 
floor  of  gold,  gage  No.  30,  sweated  or  soldered  to  it.  The  floor  is  either 
trimmed  flush  at  the  mesial  and  distal  sides  and  allowed  to  only  sHghtly 
extend  at  the  lingual  and  buccal,  or  it  is  trimmed  even  with  the  sides  of 


382 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


the  collar,  as  required  by  the  method  of  construction  of  the  cusp-cap. 
Remove  the  inner  cap  from  the  die,  place  it  in  the  mouth,  adjust  the 
outer  cap,  take  a  "bite"  and  make  models. 

Contour. — ^As  the  outer  cap  sits  on  the  inner  one,  it  presents  no 
contour.  Contour  can  be  formed  by  three  different  methods  in  ac- 
cordance with  conditions  presented,  (a)  Trim  the  floor  of  the  outer 
cap  even  with  the  collar.  Form  on  the  cap  a  wax  model  of  the  required 
cusp-cap,  that  will  also  include  the  required  contour  on  the  sides,  as 
outlined  by  the  dotted  line  in  Fig.  783 ;  remove  wax  model  and  cast  it  in 
gold.  When  cast,  fit  it  on  the  outer  cap,  making  any  necessary  altera- 
tions for  contraction  of  the  metal  in  casting,  and  wax  it  fast  around  the 
edge  to  the  collar  of  the  outer  cap.  Remove  the  outer  cap  from  the 
inner  with  the  cusp-cap  in  position,  paint  the  cavo-surface  of  the  outer 
cap  with  rouge  and  fill  it  with  investment  material.     The  cap  will  then 


?Pi^?:v-;Si-i  M 


Fig.  783.  Fig.       784. — IM, 

Investing  material. 


Fig.  786. 


Fig.   785. 


appear  as  shown  in  Fig.  784.  Solder  the  cusp-cap  to  the  outer  cap 
by  fusing  the  solder  in  small  pieces  around  the  edge  and  drawing  it  under 
the  cusp-cap,  as  described  in  Part  III,  Chapter  XIV.  This  method  of 
contouring  is  best  suited  to  short  crowns,  crowns  requiring  only  a  small 
amount  of  contour,  or  crowns  on  lower  teeth  where  weight  is  not  a 
factor. 

(b)  Trim  the  floor  of  the  outer  cap  on  all  sides  to  the  full  and  exact 
line  of  the  size  and  shape  of  the  required  contour,  as  illustrated  at 
A  and  B,  Fig.  785.  Form  a  cusp-cap  by  casting  a  wax  model  of  the 
required  form  or  by  the  cusp-button  method  (Part  III,  Chapter  VIII), 
and  solder  it  in  position  on  the  floor.  When  the  cusp-cap  is  soldered, 
fill  the  inside  of  the  crown  with  investment  material,  heat  the  crown 
slowly  to  dry  out  the  investment,  and  contour  the  collar  to  the  dotted 
line  SS,  Fig.  786,  with  as  hard-flowing  solder  as  the  collar  will  bear,  using 
the  extension  of  the  floor  as  a  shelf  on  which  to  place  the  solder.     This 


REMOVABLE  BRIDGE-WORK  383 

method  is  for  short  crowns,  or  long  ones  requiring  but  very  little  forma- 
tion of  contour. 

(c)  This  consists  in  the  addition  of  hollow  hermetically  sealed  con- 
tour to  the  mesial  and  distal  sides  of  the  outer  cap.  It  is  a  form  es- 
pecially desirable  for  large  upper  crowns  or  any  crown  to  which  it  can 
be  applied  in  which  weight  is  a  factor  to  be  considered.^  The  process 
of  construction  is  as  follows:  The  floor  of  the  outer  cap  is  trimmed  to 
extend  mesially  and  distally  to  the  size  and  form  of  the  required  contour 
less  the  thickness  of  gage  of  the  metal  that  will  be  used  to  form  the  wings 
or  contour.  Two  pieces  of  gold  plate,  gage  No.  28,  are  cut  to  form  the 
contour  wings,  each  fully  the  width  of  the  outer  collar  and  in  length 
about  one  and  three-quarters  the  diameter  of  the  cap,  from  mesial  to 
distal  side  (Fig.  787),  and  then  trimmed  and  festooned,  as  shown  in 
Fig.  788.  One  of  the  wings  is  placed  against  either  the  mesial  or  distal 
side  of  the  cap,  with  the  edge  resting  one  thirty-second  of  an  inch  from 
the  cervical  edge,  as  shown  at  A,  Fig.  789,  and  the  other  edge  resting  on 


Fig.  787.  Fig.  788.  Fig.  789.  Fig.  790.  Fig.  791. 

and  extending  above  the  floor  of  the  cap,  as  indicated  at  B.  The  con- 
tour plate  is  then  balanced  on  the  side  of  the  collar,  or  waxed  at  the 
point  to  be  soldered  and  retained  in  position  with  investing  material. 
The  cervical  edge  of  the  contour  wing  is  just  attached,  and  no  more, 
with  a  very  small  piece  of  hard  solder,  not  larger  than  a  fraction  of  a  pin 
head,  as  indicated  at  the  point  A,  Fig.  788.  It  is  next  boiled  in  acid  to 
remove  flux  and  the  wing  for  the  opposite  side  added  in  like  manner 
(Fig.  790).  The  cap  with  its  contour  plates  is  then  placed  on  the  inner 
cap  and  the  plates,  being  attached  at  only  one  point,  are  bent  out  at  an 
angle,  and  brought  around  on  the  buccal  and  lingual  sides,  and  the  ends 
trimmed  to  meet  (AA,  Fig.  791)  and  afford  the  required  contour,  as 
indicated  on  the  model  or  in  the  mouth.  Every  part  of  the  cervical 
edge  of  the  contour  plates  is  brought  to  touch  the  surface  of  the  collar 
and  the  occlusal  edge  to  rest  against  the  edge  of  the  floor  (Fig.  796). 
This  is  assisted  by  removing  the  outer  cap  from  the  inner  and  over- 
coming the  spring  of  the  gold  by  clamping  the  edge  of  the  contour  plates 
to  the  collar,  one  point  of  the  clamp  being  placed  outside  the  collar  and 
the- other  inside,  and  annealing,  but  not  heating  enough  to  fuse  the 
'  Dr.  Peeso's  method. 


384 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


solder  already  applied  to  the  contour  plate,  and  chilling  by  dipping  in 
water.  The  seam  all  around  is  then  fluxed  and  the  whole  securely 
united  with  21-carat  solder.  The  intention  in  soldering  is  to  securely 
unite  the  contour  plates  to  the  collar,  and  to  the  edge  of  the  floor,  and 
effectively  close  the  seam  with  the  least  possible  quantity  of  solder. 

The  soldering  can  be  done  by  placing  the  cap  on  a  charcoal  block, 
applying  the  solder  in  small  pieces  or  in  strip  form  on  the  buccal  and 
lingual  sides  at  the  ends  of  the  contour  plates — one  end  at  a  time — and 
drawing  the  solder  down  in  the  seam;  or  the  parts  can  be  united  by 
separately  waxing,  investing  and  soldering  one  side  at  a  time,  as  shown 
in  Fig.  792. 

Trim  the  contour  plate  to  the  Kne  of  the  surface  of  the  floor.  To 
assure  perfect  closure  of  the  parts,  the  cap  is  heated,  dipped  in  water, 
then  reheated,  and  if  the  slightest  opening  exists,  an  issue  of  steam  will 
indicate  the  spot  to  be  closed.  The  cap  is  then  ready  for  the  applica- 
tion of  the  cusp-cap. 

The  Cusp-cap. — The  cusp-cap  for  this  method,  as  in  that  previously 
described,  is  made  by  casting  from  a  wax  model  of  the  required  form. 


Pig.  792. 


Fig.  793-  Fig.  794.  Fig.  795. 


Fig.  796. 


or  by  the  use  of  a  cusp-button  (see  Methods  Nos.  4  and  6,  Part  III, 
Chapter  VIII).  A  hole  is  drilled  through  the  center  of  the  cusp-cap, 
in  the  deep  fissure,  a  little  larger  than  a  pin  head  (A,  Fig.  793,  in  section). 

The  base  of  the  cusp-cap  and  the  surface  of  the  floor  are  fluxed  and 
the  parts  wired  together,  passing  the  wire  on  both  sides  of  the  hole,  as 
,  shown  in  Fig.  794.  The  parts  are  placed  on  a  soldering  block,  cusp 
side  up,  and  slowly  heated  to  evaporate  the  moisture  from  the  flux,  and 
the  heat  then  increased  slowly  to  the  fusing  point  of  the  solder.  A  small 
piece  of  solder,  which  has  been  melted  into  a  globule,  is  placed  in  the 
hole  in  the  center  of  the  cusp-cap.  The  crown  is  uniformly  heated,  a 
small  flame  is  first  passed  over  the  surface  of  the  cap  and  then  directly 
on  the  globule,  and  it  is  fused  down  into  the  hole.  More  solder  is 
added,  and  the  flame  passed  over  the  surface  of  the  cap,  until  the  solder 
appears  at  the  edge  of  the  cusp-cap,  showing  that  it  is  completely  united 
to  the  floor  and  edges  of  the  plates. 

Another  method  that  insures  against  affecting  the  solder  on  the 
wings,  is  to  invest  the  crown  after  wiring,  nearly  up  to  the  floor,  as 


REMOVABLE  BRIDGE-WORK 


3»5 


Fig.   797. 


shown  in  Fig.  795.     When  soldered  the  crown  is  boiled  in  acid,  then 

trimmed   and   polished.     Fig.   796  shows  a  finished 

crown. 

Telescope  Crown  with  Tube   and   Split  Post. — 

When  a  telescope  crown  is  to  be  used  as  a  retaining 
abutment,  the  addition  of  a  tube  and  split  post  is  re- 
quired. When  two  telescope  crowns  alone  are  used  on 
the  same  bridge,  one  of  them  should  contain  a  tube 
and  split  post.  The  use  of  telescope  crowns  with 
tube  and  split  post  is  principally  confined  to  molars. 
The  inner  collar  having  been  formed,  the  tube 
selected  is  mounted  on  a  mandrel  and  placed  in  the 
collar  with  the  point  resting  on  the  floor  of  the  pulp- 
chamber.  A  wire  representing  the  tube  in  gage  may 
be  used  instead.  When  necessary  for  a  more  secure 
attachment,  as  in  the  case  of  an  upper  molar,  the 
tube  or  wire  is  inserted  a  short  distance  in  the  palatal 
root,  and  in  a  lower  molar  in  the  mesial  root.  The 
tube  is  to  be  paralleled  to  any  other  tube  or  tubes 
and  abutments  present,  as  described  in  the  construc- 
tion of  a  removable  bridge.  The  tube  also  must  be  parallel  to  the 
_  median  line  of  the  sides  of  the  inner  collar  to  permit 

the  post  to  move  in  and  out  freely  in  the  tube  of  the 
inner  cap  when  the  crown  is  finished. 

The  tube  and  collar,  having  been  waxed  together, 
are  removed  in  the  impression  taken  for  the  bridge  and 
a  model  made.  When  a  post  in  an  outer  cap  that 
has  been  paralleled  to  the  other  tubes  and  posts  does 
not  properly  adjust  itself  to  the  orifice  of  the  tube  in 
the  inner  cap,  the  defect  is  attributable  to  the  fact 
that  the  sides  of  the  inner  cap  are  not  shaped  in  con- 
formity with  the  line  of  the  other  abutment,  or  the 
inner  collar  had  not  been  suitably  shaped  when 
A----li4i,;jiii!i!!|.)|         constructed. 

The  sides  of  the  inner  collar  should  slightly  taper 
to  the  lines  of  the  post.     This  is  tested  by  placing  a 
narrow  separating  file  against  the  side,  as  shown  in 
U  Fig.  797.     Fig.  798  shows  a  cap  in  which  the  collar 

on  one  side  leans  toward  the  post  and  on  the  other 
side  from  it.  In  the  latter  case,  although  the  end  of 
the  root  and  cap  are  slightly  cone-shaped,  the  edge  of  the  outer  collar 
would  meet  the  inner  cap  at  the  point  A,  and  prevent  adjustment  of 

25 


Pig.   798. 


386  CROWN-,  BRIDGE;  AND  PORCELAIN-WORK 

the  post  in  the  tube.  This  can  only  be  corrected  by  trimming  the 
side  of  the  root  at  that  point  and  fitting  a  suitably  shaped  new  collar 
and  cap. 

The  tube  having  been  properly  paralleled  it  is  removed  and  a  floor 
of  gold,  gage  No.  28,  is  sweated  or  soldered  to  the  outer  collar  and  the 
excess  removed.  A  hole  is  made  through  the  floor  over  the  hole  in  the 
impression  formed  by  the  tube  or  wire  about  one  and  one-half  times 
the  diameter  of  the  tube.  This  extra  space  is  later  on  to  allow  for  the 
formation  of  a  countersunk  approach  to  the  tube  for  the  post,  as  shown 
in  section  in  Fig.  799.  The  tube  is  placed  in  the  hole  in  the  floor  and 
paralleled  with  the  other  abutments  and  also  adjusted  to  con- 
form to  the  sides  of  the  inner  cap.  The  tube  is  then  waxed 
to  the  floor.  The  wax  should  be  melted  into  the  space  around 
the  tube  and  under  the  edge  of  the  floor,  as  seen  at  B.  The 
'^^  wax  is  chilled,  the  mandrel  removed  from  the  tube,  the  cap 
and  tube  invested,  dry  asbestos  fiber  being  packed  in  the  tube.  The 
tube  is  then  soldered  to  the  floor.  In  soldering,  the  flame  should  be 
directed  around  the  tube  and  then  under  the  investment  to  draw  the 
solder  down  into  the  space  around  the  tube.  The  cap  having  been 
boiled  in  acid,  the  tube  is  cut  off  and  filed  even  with  the  floor  and  the 
cap  polished. 

The  inside  of  the  cap  is  next  varnished.     When  the  varnish  is 
dry   the  crown  is  filled  with  fusible  metal.     The  outer  collar  and  floor 
having  been  made  and  contoured,  the  location  of  the  orifice  of  the  tube 
is  marked  on  the  inner  surface  of  the  floor,  by  holding  the 
cap  firmly  on  the  die,   tapping  the  end  of  a  piece  of  wood 
over  the  spot,  or  by  passing    a  revolving  burnisher  over  it. 
A  hole  is  then  made  large  enough  only  to  admit  the  split 
post. 

For  a  telescoping  gold  crown  the  point  of  the  post  should  be  re- 
moved sufficiently  to  expose  the  slit,  so  as  to  permit  the  post  to  be 
expanded  at  the  point  instead  of  the  side,  or  so  little  of  the  gold  should  be 
left  at  the  point  of  the  post  that  it  can  be  easily  removed  and  the  post 
expanded.  The  orifice  to  the  tube  is  next  countersunk  with  a  cone- 
shape  fine  bur,  the  debris  washed  out  with  a  fine-pointed  syringe  and 
the  split  post  fitted.  Countersinking  the  neck  of  the  tube  removes  the 
contraction  caused  by  the  solder  and  enables  the  point  of  the  split 
post  to  more  readily  find  the  opening  when  the  crown  is  finished;  it 
also  allows  the  post  to  adjust  itself  better  to  the  deeper  portion  of  the 
tube  (Fig.  800  in  section). 

The  cusp-cap  is  next  made  and  fitted.  The  orifice  of  the  tube  on 
the  inner  side  of  the  cusp-cap  is  indicated  by  placing  on  its  surface  a 


REMOVABLE  BRIDGE-WORK  387 

thin  layer  of  wax  and  pressing  to  position.  A  hole  is  drilled  through  the 
cusp-cap  large  enough  to  freely  admit  the  split  post.  When  a  cast 
cusp-cap  is  used,  if  a  carbon  the  size  of  the  post  is  placed  in  position  in 
the  wax  model  before  casting,  it  will  facilitate  the  forming  of  the  hole. 
The  cusp-cap  when  constructed  is  temporarily  laid  aside. 

The  outer  cap  is  adjusted  on  the  inner  cap,  the  split  post  is  placed 
in  position  in  the  tube  with  the  slit  in  the  post  set  in  a  bucco-lingual 
direction,  the  post  cemented  with  wax  to  the  floor  of  the  outer  cap, 
removed,  invested  and  soldered  with  20-carat  solder.  The  hole  in  the 
cusp-cap  is  next  trimmed  and  enlarged  so  as  to  leave  a  slight  space  on 
all  sides  around  the  split  post  when  it  is  adjusted  to 
position. 

The  end  of  the  split  post  is  cut  off  a  little  below 
the  surface  of  the  cusp-cap  to  permit  the  end  to  be 
covered  with  solder.     The  floor  of  the  outer  cap  and 
the  base  of  the  cusp-cap  are  cleaned  and  coated  with         ^^^   g^^^ 
liquid  flux,  and  the  cusp-cap  placed  in  position  on  the 
floor  and  waxed  around  the  edge,  and  the  outer  cap  removed.     A 
strand  of  wire  may  be  used  to  secure  the  cusp-cap  immovably  to  the 
floor.     The  inside  of  the  outer  cap  is  painted  with  rouge  and  invested 
nearly  up  to  the  edge  of  the  cusp-cap,  as  shown  in  section  in  Fig.  801. 
The  wax  is  removed  and  the  investment  slowly  heated.     The  cusp-cap 
is  then  united  with  solder  fused  in  the  hole  around  the  end  of  the  post. 
The  solder  is  applied  a  Httle  at  a  time  in  small  pieces  or  globules,  or 
in  strip  form.     A  small  flame  should  be  directed  on  the  solder  and  then 
around  the  sides  to  draw  the  solder  beween  cap  and  floor  until  it  shows 
in  the  seam,  which  indicates  complete  union.     The  crown 
is  finished  in  the  usual  manner.     Fig.  802  outlines  in  sec- 
tion the  finished  crown. 
J  Removal  of  the  Cap  from  the  Die. — Any  time  during 

the  construction  that  removal  of  the  fusible  metal  from  the 
cap  is  required,  the  die  and  crown  are  placed  in  boiling 
water  and  the  metal  melted  out.  The  crown  on  removal  from  the 
water  is  placed  for  a  time  or  boiled  in  nitric  acid,  to  insure  the  entire 
removal  of  the  fusible  metal,  as  a  minute  particle  left  adhering  would 
cause  a  perforation  when  the  crown  is  heated. 

Tube  and  Split-post  Anterior  Crowns 

Incisors,  Cuspids  and  Bicuspids  with  Porcelain  Facings. — For  these 
crowns  the  end  of  the  root  is  given  a  form  similar  to  that  required  for 
a  collar  crown  (Richmond).     The  sides  of  the  root  must  be  shaped  and 


L  " 


388 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


the  canal  reamed  for  the  tube  so  that  it  shall  be  parallel  with  the  other 
abutments.  The  end  of  the  root  is  trimmed  in  a  slanting  plane  from 
the  lingual  to  the  cervico-labial  side.  At  the  cervico-labial  section 
the  end  of  the  root  should  be  trimmed  not  more  than  one-thirty-second 
of  an  inch  under  the  gum  margin,  or  only  enough  to  hide  the  edge  of 
the  collar.  When  more  of  that  part  is  removed  the  edge  of  the  gum  is 
liable  to  crowd  over  the  edge  of  the  floor  of  the  cap  and  be  pinched  in 
the  reinsertion  of  the  crown  (Fig.  803).  The  canal  is  enlarged  lin- 
gually  a  little  with  a  reamer,  so  as  to  permit  as  good  an  attachment  as 
possible  for  the  end  of  the  split  post,  and  later  facilitate  correct  placing 
of  the  facing.  The  end  of  the  root  should  be  left  extending  slightly 
above  the  gum  until  the  collar  has  been  fitted. 

The  collar  is  made  of  coin  or  22-carat  gold,  gage  No.  30.  After 
the  collar  is  fitted  the  end  of  the  root  and  collar  are  trimmed  to  the 
same  level,  as  indicated  in  Fig.  804.  The  edge  of  the  collar  and  the 
floor  must  meet  at  every  point  and  are  either  sweated  or  soldered  to- 


FlG.  803. 


Pig.  804. 


Fig.  805. 


gether.  If  soldered,  the  smallest  possible  quantity  of  hard  solder  should 
be  used.  The  surplus  metal  of  the  floor  is  removed  and  a  hole  made 
through  the  floor  for  the  tube. 

The  hole  in  the  floor  for  the  tube,  as  in  the  case  of  the  telescope 
crown  with  tube  and  split  post,  should  be  made  at  least  half  again 
larger  than  the  tube  to  allow  the  solder  to  flow  around  the  tube  and 
permit  the  orifice  to  be  countersunk  (Fig.  805).  The  cap  is  adjusted 
on  the  root,  the  tube  mounted  on  a  mandrel  and  placed  in  the  reamed 
canal  and  paralleled  to  the  other  abutments.  The  tube  is  then  waxed 
to  the  cap  and  removed. 

The  tube  and  cap  should  now  be  examined  to  see  if  the  fine  of  the 
tube  with  the  collar  is  such  as  will  permit  the  outer  cap  when  finished 
to  move  on  and  off  without  interference.  This  is  easily  determined 
by  the  eye — with  a  mandrel  in  the  tube — or  more  positively  by  placing 
a  flat  separating  file  against  the  sides,  the  same  as  in  the  case  of  a  tele- 
scope crown.  Fig.  806  shows  a  correct  alignment  of  the  tube,  and 
Fig.  807  an  incorrect  alignment.     If  the  alignment  is  incorrect,  it  must 


RRMO Vy\  BLE  BRIDGE- WORK 


be  changed  by  trimming  the  root  and  making  a  new  collar.  If  correct, 
the  mandrel  is  seized  with  pliers,  a  small  chisel  is  placed  against  the 
edge  of  the  tube,  which  is  pushed  off  the  mandrel,  invested  and  soldered 
to  the  floor.  The  solder  is  flowed  down  and  around  the  tube,  as  ex- 
plained in  the  construction  of  a  telescope  crown  with  a  tube  and  split 
post. 

Having  been  boiled  in  acid,  the  tube  is  cut  off  and  ground  level  with 
the  floor.  The  neck  of  the  tube  is  countersunk  with  a  cone-shape 
finishing  bur,  and  reamed  enough  to  correct  the  contraction  of  the 
solder.  The  cap  is  then  polished,  the  debris  in  the  tube  removed  by  a 
fine-pointed  syringe  with  water,  the  tube  dried  and  the  split  post  fitted. 

The  Outer  Cap. — This  is  a  half-collar  cap,  retained  by  the  spHt 
post  fitted  to  the  tube  of  the  inner  cap.  It  is  to  carry  a  porcelain- 
faced  gold  crown  or  one  of  porcelain.  The  half-collar  lessens  the  strain 
on  the  split  post  and  aids  in  strengthening  the  crown.     To  avoid  irri- 


FlG. 


Fig.  806. 


Fig.  807. 


Fig.   809. 


tation,  the  edge  of  the  half  collar  must  be  trimmed  free  of  the  gum 
margin  one-sixteenth  inch. 

To  prevent  any  accidental  disturbance  of  the  form  of  the  inner  cap 
during  the  fitting  of  the  outer  one  and  to  facilitate  the  work,  the  inside 
of  the  inner  cap  should  be  filled  with  fusible  metal  that  melts  below 
212°  F.  This  is  best  done  by  inserting  the  cap  in  moldine  in  a  flask  ring, 
as  shown  in  Fig.  808. 

The  half  collar  is  made  of  the  same  plate  as  the  inner  collar  gage 
No.  30.  It  is  most  easily  constructed  by  first  forming  the  outer 
collar  to  entirely  encircle  the  inner  collar.  The  edge  is  trimmed  even 
with  the  floor  of  the  inner  cap,  a  floor  of  gold  plate,  gage  No.  28, 
adapted,  collar  and  floor  removed  and  united  to  it  with  21 -carat  solder. 
In  uniting  the  collar  to  the  floor  the  attachment  with  the  solder  should 
be  confined  to  the  lingual  section  that  is  to  remain.  This  is  best  ac- 
complished by  notching  the  collar  on  both  sides,  as  shown  in  Fig.  809, 


390 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


The  solder,  if  only  a  small  quantity  is  used,  will  be  confined  to  the 
lingual  section  by  the  vacancy  caused  by  the  notches  in  the  collar, 
which  will  consequently  leave  the  labial  portion  ununited  and  easy  to 
remove. 

The  floor  of  the  outer  cap  is  next  trimmed  even  with  the  sides  of  the 
collar.  The  outer  cap  is '  fitted  on  the  inner,  burnished  or  swaged 
to  its  surface,  and  the  floor  perforated.  It  is  then  held  firmly  on  the 
inner  cap,  and  the  hole  enlarged  sufficiently  to  allow  the  post  to  pass 
through.  The  post  is  waxed  to  the  floor,  the  cap  and  post  removed, 
invested  and  soldered  together. 

The  slit  in  the  spHt  post  should  be  placed  in  a  labio-lingual  direction 
for  strength,  as  shown  in  Fig.  8io.  The  loose  labial  section  of  the 
collar  in  front  of  the  notches  is  next  removed  and  the  lingual  section 
remaining  trimmed  and  finished,  as  shown  at  A,  Fig.  8ii,  and  at  B, 


Fig.  8io. 


Pig.  8ii. 


Pig.   8i2. 


in  position  on  the  inner  cap.  The  inner  cap  is  released  from  the  die  with 
boiling  water  and  nitric  acid.  If  properly  constructed  in  all  its  details 
the  result  will  be  a  crown  base  reliable  as  a  retaining  abutment  and 
uniform  in  adjustment  and  removal.  The  porcelain  facing  is  fitted 
to  the  outer  cap,  the  outer  cap  removed,  invested,  and  facing  and  cap 
united  with  solder  the  same  as  in  the  case  of  an  ordinary  crown. 


Converging  Teeth  and  Roots 

When  a  molar  converges  as  shown  in  Fig.  812,  it  can  be  paralleled 
to  the  anterior  abutment,  for  a  telescope  gold  crown,  by  shaping  as 
indicated  by  the  line  A. 

For  porcelain-faced  crowns,  when  the  convergence  is  of  the  charac- 
ter illustrated  in  Fig.  813,  the  tubes  and  split  posts  must  be  located  in 
the  crowns  instead  of  the  roots.  The  sides  of  the  roots  are  trimmed 
parallel.  The  distal  sides  require  very  little  trimming  (Fig.  814). 
The  inner  caps  are  made  and  fitted  to  the  roots.     The  split  posts  are 


REMOVABLE  BRIDGE-WORK 


391 


formed  of  half-round  platinized  gold  wire.  The  slit  in  the  portion  of 
the  post  inserted  in  the  root  is  soldered  together,  leaving  the  section 
open  that  is  to  extend  above  the  floor  of  the  cap.  The  posts  are  to  be 
bent  at  a  point  in  the  canal  a  little  below  the  floors,  so  that  the  portion 
extending  above  the  floors  shall  be  parallel.  The  canals  should  be 
reamed  sufficiently  to  permit  the  posts  to  be  placed  as  far  as  possible 
toward  the  lingual  side,  to  leave  space  for  the  porcelain  facing,  as 


Pig.  813. 


Fig.  814. 


illustrated  in  Fig,  815.  Holes  are  made  in  the  floors  of  the  inner  caps 
to  allow  the  posts  to  pass  through.  The  posts  are  then  attached  to  the 
floors  with  a  small  quantity  of  wax.  Plaster  is  placed  over  each  cap 
and  post,  they  are  removed,  invested,  the  plaster  and  wax  removed  and 
posts  soldered  to  the  floors.  Any  excess  of  solder  present  must  be 
removed  perfectly  even  with  the  floor. 


Fig.  815. 


Pig.  816. 


The  outer  caps  are  constructed  with  floors  of  gold  plate  gage  No.  28. 
Tubes  with  closed  ends  are  fitted  over  the  posts  and  holes  made  in  the 
floors  large  enough  to  allow  them  to  pass  through.  The  tubes  are 
attached  to  the  floor  of  each  outer  cap  with  wax,  removed,  invested 
and  soldered  to  the  floor.  Investing  material  and  a  piece  of  iron  wire 
or  a  nail,  must  be  inserted  into  each  tube  to  retain  it  in  position  when 
the  wax  is  removed,  as  shown  in  Fig.  816. 

The  porcelain  facing  is  ground  in  position  on  the  cap.  When  neces- 
sary a  Httle  of  the  porcelain  between  the  pins  can  be  removed  to  better 


392 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Fig.  817. 


accommodate  the'  tube.  The  facing  is  backed  with  thin  platinum.  In 
soldering  the  facing  or  bridge,  the  investing  material  and  wire  should  be 
again  inserted  into  the  tube  to  prevent  its  displacement. 

The  bulky  form  on  the  lingual  side  of  this  style  of  crown  will  not 
permit  its  use  in  many  cases  for  superior  cuspids.  In  cementation 
the  inner  caps  should  be  first  placed  in  position  with  the  cement  and 
immediately  the  bridge  set  over  them.  Vaselin  placed  in  the  tubes 
and  outer  caps  will  prevent  invasion  of  the  cement. 

Retaining  Inlay  Abutments 

Retaining  Abutments. — For  attachments  of  this  style,  the  pulp  is 
removed,  but  the  natural  crown  is  preserved.  The  attachment  consists 
of  a  countersunk  gold  inlay  with  a  tube  into  which  fits  a  supplementary 
or  m.ale  inlay,  with  a  split  post.  This  form  of 
attachment  is  used  where  it  is  desirable  to 
preserve  the  abutment  tooth  or  teeth  as  nearly 
as  possible  intact,  as  in  a  case  where  a  sound 
central  is  used  as  an  abutment  for  an  adjoining 
central  or  lateral.  It  is  preferably  used  in  a 
cuspid  which  is  to  act  as  an  abutment  to  support 
the  lateral  with  the  assistance  of  a  lug  on  the  central.  It  also  is  used 
as  an  anterior  abutment  to  a  molar  abutment,  and  in  cases  where 
the  shape  or  position  of  a  tooth  suggests  its  use  as  being  preferable  to 
a  crowning  operation. 

Bicuspids  and  Molars. — A  molar  will  be  used  to  explain  the  method. 
The  pulp  is  removed  and  canals  treated.  The  cavity 
for  the  inlay  is  made  in  the  occlusal  surface  about 
one-hall  the  length  from  mesial  to  distal  side,  as  shown 
at  A,  Fig.  817,  and  in  the  mesial  or  approximal  side, 
large  enough  to  furnish  room  for  the  matrix  or  female 
inlay  that  is  to  carry  a  supplementary  or  male  inlay 
with  a  tube  and  split  post,  as  shown  at  B, 

Fig.  818  outlines  in  section  the  assembled  por- 
tions of  a  removable  inlay  attachment  with  a  split 
post.  The  orifice  to  the  canals  and  the  body  of  the 
pulp-chamber  are  first  filled  with  cement,  preferably  oxychlorid  of 
zinc.  To  prevent  pressure  on  the  inlay  splitting  the  tooth,  the  side 
walls  should  be  made  nearly  straight,  slanting  but  very  slightly  out- 
ward— and  the  bottom  of  the  cavity  flat  or  nearly  so.  Provision  for 
the  tube  should  be  made,  which  should  extend  to  the  floor  of  the  pulp- 
chamber  and,  if  necessary  for  security,  be  inserted  a  short  distance 
into  one  of  the  roots. 


Fig.  818. — A, 
Matrix  or  female 
inlay;  B,  supple- 
mentary or  male 
inlay;  C,  tube;  D, 
bent    splint    post. 


REMOVABLE  BRIDGE-WORK 


393 


Pig.  819. 


The  palatal  root  of  an  upper  molar  or  the  mesial  root  of  a  lower 
molar  is  usually  selected.  The  tube  should  be  the  largest  the  tooth 
will  properly  allow,  so  as  to  carry  a  correspondingly  large  tube,  if 
possible,  gage  No.  5  or  6. 

The  Matrix  or  Female  Inlay.— This  can  be  made  by  the  direct 
method  but  not  with  the  same  facility  or  accuracy  as  by  the  indirect, 
consequently  the  latter  will  be  described.  The  cavity  having  been 
shaped,  as  outHned  in  Fig.  817,  an  impression  is  taken  with  impression 
compound  and  an  amalgam  die  made.  A  cast  matrix  of  gold  alloyed 
with  three  to  five  per  cent,  of  copper  is  made  for  the  cavity.  This  is 
done  by  shaping  a  sheet  of  wax,  about  one-sixteenth  inch  in  thickness, 
to  the  cavity  and  shghtly  over  the  margins  (Fig.  819).  The  wax  is 
perforated  over  the  indentation  in  the  die  for  the  tube  and  a  carbon 
inserted.  A  sprue  wire  is  inserted  in  the  edge  of  the  wax,  and  the  wax 
matrix  is  lifted  from  the  cavity,  in- 
vested and  cast. 

The  cast  matrix  is  first  fitted  to 
the  die  and  next  in  the  tooth.     The 
edge  of  the  casting  is  brought  close 
to  the  margins  of  the  cavity  with  a 
piece  of  orange  wood,  tapped  on  the 
end  with  a  mallet  and  a  revolving 
burnisher  passed  over  the  part.     The 
hole   in  the  matrix  for  the  tube  is 
enlarged  to  fully  the  size  of  the  di- 
ameter of  the  tube  (Fig.  820).     The 
tube  mounted  on  a  mandrel,  is  in- 
serted in  the  hole  (Fig.  821  in  section)  surrounded  with  wax  and  par- 
alleled to  the  other  abutments.     Matrix  and  tube  are  removed  and 
then  the  mandrel  from  the  tube,  and  matrix  and  tube  are  invested  and 
united  with  solder. 

The  matrix  and  tube  having  been  adjusted  in  the  cavity  to  deter- 
mine the  accuracy  of  the  position  of  the  tube,,  they  are  removed  and 
the  extended  end  of  the  tube  trimmed  level  with  the  floor  of  the  matrix, 
and  its  orifice  shghtly  countersunk,  so  thaf  the  spHt  post  may  enter 
more  freely  (Fig.  822). 

The  gold  of  the  side  walls  of  the  matrix  cavity  are  to  be  trimmed  so 
as  to  give  them  proper  form  in  detail.  The  forward  section  of  the 
cavity  should  be  deep  and  narrow  for  strength  in  preference  to  being 
made  broad  and  flat.  The  cavity  having  been  properly  shaped  the 
surface  of  the  gold  is  then  smoothed  and  burnished  with  a  revolving 
burnisher. 


Fig  820..    Fig.  822. 


Fig.  821. 


394 


CROWN  ,  BRIDGE-,  AND  PORCELAIN-WORK 


Split  Post  and  Supplementary  or  Male  Inlay. — A  post  is  fitted  to 
the  tube.  The  sHt  in  the  post  should  be  placed  in  a  labio-lingual  direc- 
tion. The  slit  at  the  point  of  the  post  should  be  left  closed,  so  that  it 
will  not  open  when  the  post  is  bent.  The  point,  though,  should  be  filed 
flat,  moving  the  file  in  the  line  of  the  slit,  and  the  edges  slightly  rounded. 
Enough  should  be  removed  at  the  point  to  closely  approach  the  slit 
so  that  at  any  time,  if  desired,  the  filing  of  a  slight  groove  will  reach 
the  slit  and  permit  the  post  to  be  expanded  from  the  point. 

The  matrix  to  the  supplementary  or  male  inlay  is  made  by  shaping 
and  burnishing  a  matrix  of  pure  gold,  gage  No.  36, 
or  /-looo  platinum,  into  the  female  cavity  and  well 
over  the  edges,  frequently  removing  the  matrix  and 
annealing.  A  hole  is  made  in  the  matrix  over  the 
tube,  the  split  post  inserted,  the  line  of  the  floor 
of  the  matrix  marked  on  the  side  of  the  post,  the 
post  withdrawn  and  bent  level  with  the  floor  of  the 
matrix,  preferably  using  a  pin  bender  instead  of  a 
pin  vise  or  pliers. 

A  Pin  Bender. — ^A  post  can  be  bent  with  a  pin 

vise,  but  the  bending  is  best  done  by  the  use  of  a 

pin  bender,  which  is  really  a  tube  in  which  the  post 

fits  accurately.     The  set  consists  of 

three  tubes.     The  holes  in  the  ends 

of  each  are  proportionately  increased 

in  size,  so  as  to  accommodate  six  sizes 

...... —  of  posts,  as  shown  in  Fig.  823.     Select 

a   size  corresponding   to    the   post, 

anneal  and  insert  the  post — closed 
end  first — as  shown  in  Fig.  824,  and 
bend  it  to  the  required  angle,  anneal- 
ing two  or  three  times. 
Pig.  823.  Fig.  824.  ^j^^  ^^.^^^  ^^  ^-^^  ^^^^  -^  ^i^^-^^^^y 

oiled.  The  male  matrix  is  annealed,  adjusted  in  the  cavity  and  the 
post  inserted.  Adhesive  wax  is  then  melted  into  the  matrix  and 
arouDd  the  post,  and  pressure  exerted  on  the  wax  to  bring  all  parts  to 
position.  The  wax  is  chilled,  the  matrix  and  post  removed,  invested 
and  the  matrix  filled  with  coin  gold.  It  is  next  boiled  in  acid,  the 
edges  trimmed  to  that  of  the  first  or  female  inlay — revolving  the 
stones  from  the  center  outward — then  polished. 


Variations  in  Method 

A  method  of  constructing  the  first  or  female  section  of  inlay  abut- 
ments, is  to  cast  it  with  the  tube  in  position. 


REMOVABLE  BRIDGE-WORK  395 

Another  method  is:  Swage  in  the  cavity  a  piece  of  pure  gold  gage 
/■fooO)  oil  the  surface,  burnish  and  swage  over  it  another  piece  of  the 
same  gage  of  gold  and  punch  a  hole  through  each  side  of  the  second 
piece  with  a  punch  forceps.  Invest  and  unite  the  two  matrices 
with  a  particle  of  solder,  fused  through  the  two  holes  in  the  sides. 
Insert  the  matrix  in  the  cavity  and  burnish.  Add  another  layer  of 
gold  to  the  matrix  in  the  same  manner  when  the  case  so  suggests.  Fit 
the  matrix  in  the  cavity,  trim  and  burnish  the  edges,  place  the  tube 
in  position,  remove  and  solder.  By  this  method  a  perfect  fitting  edge 
can  be  obtained  for  the  female  inlay. 

In  cases  where  extensive  decay  has  involved  the  occlusal  surface, 
shorten  the  cusps,  bevel  and  cover  the  edges  to  avoid  the  possibility 
of  the  tooth  splitting  (Fig.  825). 

Incisors  and  Cuspids. — The  use  of  the  inlay  abutment  attachment 
for  the  front  teeth  is  confined  chiefly  to  upper  central  incisors  and  cus- 
pids, and  lower  cuspids.     It  is  seldom  applied  to  upper  laterals  and 


Pig.  825.  Fig.  826. 

never  to  lower  incisors,  as  the  teeth  are  too  small.  To  explain  the 
construction,  a  cuspid  will  be  used  as  a  typical  case.  An  opening  is 
made  at  the  lingual  side  of  the  crown  in  the  line  of  the  pulp-canal,  the 
pulp  devitalized,  removed,  the  foramen  closed  with  gutta-percha, 
and  the  canal  filled  with  zinc  oxychlorid.  (See  Part  II,  Chapter  III.) 
The  treatment  must  be  so  conducted  as  not  to  affect  the  shade  of  the 
tooth. 

The  cavity  in  the  crown  is  enlarged  and  shaped  for  the  inlay  and  the 
canal  reamed  for  the  tube,  as  shown  in  Fig.  826.  The  side  of  the  cavity 
approximately  to  the  bridge  should  be  shaped  so  as  to  allow  as  nearly  as 
possible  direct  connection  with  it,  as  indicated  at  A.  To  avoid  weaken- 
ing the  labial  section  of  the  crown,  the  reaming  for  the  tube  should  be 
carried  lingually  as  far  as  it  properly  can  be,  and  kept  within  the  line 
of  the  axis  of  the  tooth.  The  sides  of  the  cavity  must  taper  slightly 
to  the  line  of  the  tube.  The  edges  should  have  a  slight  bevel.  The 
canal  is  reamed  to  receive  a  No.  4  or  No.  5  tube.  Centrals  generally 
take  a  smaller  size.     The  depth  varies  in  accordance  with  the  size  and 


396 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


length  of  the  root,  but  usually  it  is  from  five-sixteenths  to  three-eighths 
of  an  inch. 

The  first  or  female  inlay  is  made  either  by  the  direct  or  indirect 
method.  As  the  process  of  the  formation  by  either  method  is  about  the 
same,  the  indirect  will  preferably  be  explained.  The  tube  having 
been  fitted  to  the  canal,  is  removed. 

To  Take  the  Impression. — Fit  a  brass  wire  in  the  canal  the  size  of 
the  selected  tube.  Soften  a  small  piece  of  compound,  slightly  heat  the 
wire  and  surround  it  with  the  compound.  Wet  the  cavity,  force  the 
wire  to  position  in  the  canal,  press  the  compound  around  the  wire, 
into  the  cavity  and  over  the  edges,  chill  and  remove.  An  amalgam  die 
is  then  made.  To  enable  the  amalgam  to  be  properly  pressed  into 
the  impression,  embed  the  impression  in  a  funnel  of  plaster,  as  shown  in 
section.  Fig.  827.     (See  Part  I,  Chapter  V.)     When  the  amalgam  has 


Pig.  827. 


Fig.  828. 


Fig.  829. 


set,  the  wire  and  compound  are  removed.  The  die  will  be  a  replica  of 
the  cavity  and  canal. 

The  surface  of  the  die  is  lubricated,  and  then  wiped  with  cotton  to 
prevent  adhesion  of  the  wax.  The  tube,  mounted  on  a  mandrel,  is 
inserted  in  the  canal,  the  cavity  filled  with  wax  pressed  well  around  the 
tube,  and  then  trimmed  to  a  uniform  thickness  over  the  surface  of  the 
cavity,  leaving  a  slight  surplus  beyond  the  edge,  into  which  the  sprue 
wire  is  inserted.  The  wax  is  removed,  the  mandrel  seized  with  pliers, 
and  the  tube  pushed  off  the  mandrel.  The  tube  is  filled  with  asbestos, 
the  wax  model  invested,  and  cast  with  pure  gold  alloyed  with  two  per 
cent,  of  copper  (Fig.  828). 

Some  practitioners  prefer  to  first  cast  the  matrix  inlay  without  the 
tube,  placing  carbon  in  the  wax  model  instead.  After  the  inlay  is  cast 
and  fitted,  the  tube  is  inserted,  invested  and  soldered  in  posi  ion. 

At  this  stage  the  work  may  be  fitted  to  the  mouth,  to  determine  its 


REMOVABLE  BRIDGE-WORK  397 

accuracy  respecting  adaptation  and  occlusion.  The  remainder  of  the 
construction  of  the  inlay  attachment  can  be  done  either  directly  in  the 
mouth  or  indirectly  on  the  model.  The  tube  is  cut  off  at  the  floor  of 
the  cavity  and  the  inlay  trimmed  and  symmetrically  shaped.  Enough 
gold  is  removed  to  make  space  for  the  supplementary  or  male  inlay, 
leaving  the  gold  at  the  edge  of  the  cavity  intact,  as  shown  in  Fig. 
829.  The  orifice  to  the  tube  should  be  slightly  countersunk,  and  the 
contraction  at  the  neck  from  the  casting  or  soldering  removed  with  a 
dull  cone-shape  finishing  bur.  The  surface  of  the  cavity  and  the  orifice 
of  the  tube  are  smoothed  and  polished  and  a  revolving  burnisher  lightly 
passed  over  the  surface. 

Insertion  of  the  Split  Post. — The  split  post  is  next  fitted  in  the  tube. 
It  should  be  nearly  twice  the  length  of  the  tube,  and  fit  accurately  but 
easily.  The  point  of  entrance  of  the  tube  is  marked  on  the  post.  The 
post  is  removed  and  bent  one-thirty-second  of  an  inch  farther  from  the 
cavity  towards  the  shank  than  the  mark,  using  a  pin  bender  as  already 
described. 

The  Supplementary  Inlay. — This  is  best  made  by  the  matrix  method. 
A  piece  of  pure  gold  plate,  gage  No.  36,  or  yiooo  to  3^^00  0  platinum,- 
preferably  the  latter,  is  shaped  to  the  cavity  and  into  the  orifice  of 
the  tube.  When  gold  plate  is  used,  it  is  removed  and  the  metal  that 
has  been  burnished  into  the  orifice  of  the  tube  is  removed  by  grinding 
it  on  the  cavo-side  of  the  matrix,  making  the  hole  a  little  larger  than 
the  post,  so  as  to  allow  it  to  enter  the  tube  freely.  When  platinum  foil 
is  used  it  is  trimmed  at  the  orifice  of  the  tube. 

The  orifice  of  the  tube  is  vaselined,  the  matrLx  adjusted  in  the  cavity, 
the  post  inserted  in  position  and  the  wax  melted  with  a  heated  spatula 
into  the  matrix  and  around  the  post.  The  matrix  and  post  are  re- 
moved, invested,  and  the  matrix  filled  with  coin  gold.  The  gold  should 
be  drawn  around  the  shank  of  the  post,  by  heat  applied  under  the  in- 
vestment. After  being  cleaned  in  the  usual  manner,  it  is  adjusted 
to  the  inner  or  female  inlay.  The  edges  should  be  left  a  little  flush  until 
the  final  finishing  when  the  bridge  is  inserted.  In  finishing,  stones  and 
polishing  points  should  be  revolved  outward  from  the  center. 

The  attachment  is  now  ready  for  connection  to  the  bridge,  to  which 
che  shank  of  the  post  is  waxed,  and  the  wax  chilled.  The  bridge  is 
removed,  the  tube  is  held  by  the  fingers,  and  by  pressing  on  the  post 
with  the  point  of  an  instrument,  the  inner  or  male  inlay  is  released  and 
the  bridge  with  post  invested. 

Another  method  for  removing  the  post  is  to  heat  the  point  of  a  stick 
of  hard  adhesive  wax  and  attach  it  to  the  metal  over  the  post,  chill  and 
pull  the  post  from  the  tube. 


398  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Use  of  Swaged  First  or  Female  Matrix. — Female  matrices  for  in- 
cisors and  cuspids  may  preferably  be  made  by  the  swaging  instead  of 
the  casting  method,  using  pure  gold  plate  as  heavy  as  the  size  and  shape 
of  the  cavity  will  admit,  which  varies  from  gage  No.  32  to  No.  36,  or 
Ho  00  platinum.  First  shape  the  gold  or  platinum  matrix  in  a  fusible 
metal  die  of  the  cavity  taken  from  the  amalgam  die,  and  then  transfer 
it  to  the  amalgam  die  for  finishing.  The  matrix  should  be  extended 
well  over  the  margins  of  tne  cavity.  When  a  platinum  matrix  is  used, 
it  should  be  reinforced  after  shaping  it  to  the  cavity,  by  veneering  the 
outer  surface  with  two  or  three  applications  of  pure  gold,  readapting 
the  matrix  to  the  cavity  between  the  applications.  In  this  way  a 
most  accurately  fitting  matrix  is  obtained.  To  reinforce  the  matrix, 
paint  the  cavo-surface  with  rouge,  place  pure  gold — a  few  small  pieces 
at  a  time —  in  the  matrix  and  fuse  it  by  holding  the  rriatrix  in  a  Bunsen 
flame.  Flux  may  be  used,  but  is  not  necessary.  (See  "Matrix  Gold 
Inlay,"  Part  III,  Chapter  XVII.)  The  tube  is  next  fitted  and  soldered 
in  position  with  coin  gold.  The  subsequent  procedure  is  conducted  the 
same  as  with  a  cast  matrix.  The  matrix  method  is  preferable  to  casting 
in  the  construction  of  these  attachments  for  small  anterior  teeth. 

Supporting  Abutments 

This  form  consists  of  a  lug,  with  or  without  an  anchorage  point, 
that  rests  in  a  countersunk  gold  filling  or  inlay,  or  a  socket  formed  in  an 
artificial  crown.  It  supports  and  steadies  one  end  of  the  bridge  but 
does  not  retain  it. 

A  lug  attachment  on  one  end  of  a  bridge,  in  conjunction  with  a 
reliable  retaining  abutment  on  the  other,  is  usually  suflicient  to  support 
a  bridge  of  one  or  two  teeth.  On  the  mandible  in  conjunction  with  a 
retaining  molar  abutment  it  will  in  many  cases  afford  additional  reliable 
supports  to  a  bridge  of  two  and  occasionally  three  teeth.  It  can  also  be 
used  to  furnish  additional  support  to  a  large  bridge  with  two  or  more 
retaining  abutments. 

In  teeth  with  vital  pulps,  the  cavity  should  be  made  large  enough 
without  impinging  on  the  pulp  to  accommodate  the  lug  and  allow  a  sub- 
stantial lining  of  gold  between  it  and  the  walls.  To  prevent  displacer 
ment,  an  undercut  form  should  be  given  the  cavity  for  a  filling,  and  a 
retentive  form  for  an  inlay.  As  retentive  a  form  as  possible  should  also 
be  given  the  lug.  As  the  lug  will  be  adjusted  and  removed  in  an  occlu- 
sal direction,  calculation  should  be  made  accordingly. 

The  cavity  in  a  cuspid  is  usually  given  the  form  illustrated  in 
Fig.  830.     The  filling  or  inlay  may  be  slightly  exaggerated  in  contour  by 


REMOVABLE  BRIDGE-WORK  399 

expanding  its  bulk,  as  illustrated  at  A,  Fig.  831,  by  extending  it  over  the 
margin  of  the  cavity,  to  increase  the  depth  of  the  slot  for  the  lug.  If 
a  filling  is  used  it  should  be  made  entirely  of  cohesive  gold  foil  thor- 
oughly condensed.  When  an  inlay  is  used,  the  slot  for  the  lug  may  be 
cut  in  the  inlay  after  it  is  cast,  or  a  depression  maybe  made  in  the  wax 
model,  and  the  slot  shaped  additionally  after  the  casting.  The  lug  is 
made  of  clasp  gold  wire,  gage  12  to  14,  the  gage  being  regulated  by  the 
size  of  the  tooth  and  the  stress  it  will  have  to  withstand.  Usually 
some  trimming  of  the  wire  is  necessary. 

A  slot  in  a  filling  is  best  cut  by  first  drilling  an  indentation  in  the 
center  or  slightly  past  it  on  the  lingual  side  (A,  Fig.  832),  close  to  the 
bottom  of  the  cavity  with  a  spear-pointed  drill,  and  then  shaping  it  with 
a  pear-shape  bur  to  the  size  of  the  wire  used.  A  slot  (B)  is  cut  the 
same  size  as  the  hole,  from  its  orifice  to  the  side  of  the  filling  or  inlay. 
The  removal  of  gold  for  the  slot  should  be  so  conducted  as  not  to  weaken 
the  efl&ciency  of  the  filling  or  inlay. 


Pig.  830.  Fig.  831.  Pig.  832. 

The  point  of  the  wire  lug  is  slightly  rounded  and  the  end  bent  at  a 
right-angle  and'  filed  (C)  so  that  the  point  rests  in  the  indentation  at 
the  end  of  the  slot.  The  shank  of  the  wire  lug  is  made  long  enough 
to  extend  to  the  backing  of  the  adjoining  dummy,  so  that  it  can  be 
soldered  under  the  cusp-cap,  if  one  be  present. 

In  bicuspids  and  molars  with  vital  pulps,  the  cavity  of  the  filling 
or  inlay  is  extended  about  two-thirds  or  three-fourths  across  the  occlu- 
sal surface,  and  down  on  the  side  approximately  to  the  bridge,  so  as  to 
give  such  a  length  to  the  filling  or  inlay  as  will  admit  of  a  proportionate 
length  to  the  wire  lug,  as  shown  in  Fig.  833.  Bicuspids  do  not  admit 
of  the  use  of  a  large  wire  lug  except  when  pulpless.  A  much  more 
substantial  wire  lug  can  be  applied  to  molars. 

To  fill  in  the  space  on  the  sides  and  around  a  wire  lug  and  anchorage 
point  so  that  there  shall  be  no  perceptible  seam:  Burnish  a  matrix  of 
Ho 00  platinum  foil  in  the  groove,  and  fill  the  matrix  with  wax  before  or 
after  the  lug  is  attached  to  the  bridge.     Warm  the  wire  lug  and  press  it 


400 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


to  position  in  the  wax  of  the  matrix,  remove,  invest,  wash  out  the  wax 
and  melt  hard  solder  in  the  matrix  around  the  wire  lug,  trim  and  adjust. 
The  additional  metal  increases  the  size  and  strength  of  the  lug  and 
causes  it  to  assume  the  form  of  a  supplementary  inlay.  If  the  cavity 
in  the  inlay  is  given  the  slight  retention  form  seen  in  Fig.  833,  the  lug  is 
rendered  additionally  secure. 

The  greatest  stress  on  a  support  of  this  form  is  on  the  part  that  spans 
the  space  between  the  bridge  and  the  entrance  to  the  slot  of  the  abut- 


PlG.  833. 


Pig.  835. 


Fig.  836. 


ment.  This  portion  can  be  reinforced  quite  effectively  by  flaring  the 
entrance  to  the  slot,  as  shown  at  A,  A,  Fig.  834,  burnishing  the  platinum 
matrix  to  the  flare,  and  extending  the  matrix  under  the  lug  to  the 
dummy,  then  investing  and  filling  the  matrix  with  solder.  Fig.  835 
shows  the  reinforced  attachment  finished  in  the  matrix  of  the  molar, 
and  Fig.  836  the  same  in  a  bicuspid. 

A  socket  for  a  lug  attachment  in  a  gold  crown  is  described  in  Part  IV, 
Chapter  III,  Figs.  603  to  609  inclusive. 


Special  Forms  of  Attachments 

Collar  and  Partial  Cap. — This  is  a  form  of  attachment  made  to  fit 
over  a  gold  crown.     It  is  seldom  used  on  a  natural  tooth.     For  the 


Y^L 


A 


Pig.  837. 


Fig.  838. 


Fig.  839.  Pig.  840. 


gold  crown,  the  sides  of  the  tooth  are  to  be  shaped  straight  and  parallel 
to  the  sides  of  any  other  supporting  crown  or  Hne  of  attachment.  A 
straight-sided  gold  crown  is  made  and  fitted.  The  gold  crown  is 
removed,  a  strip  of  paper  wound  around  it,  and  fusible  metal  melted 
and  poured  into  crown  and  paper  tube.     This  forms  a  die  of  the  crown 


REMOVABLE  BRIDGE-WORK  401 

with  a  shank,  as  seen  in  Fig.  837.  The  crown  is  encircled  with  a  strip 
of  pure  gold,  about  gage  No.  30,  one  part  of  which,  B,  Fig.  838,  will 
extend  above  the  remainder  in  the  form  shown  in  Fig.  839.  The  sec- 
tions of  the  gold  at  A,  A,  Fig.  838,  are  to  reach  from  the  edge  of  the  neck  of 
the  crown  to,  or  slightly  above  the  occlusal  surface.  The  gold  is  fitted 
evenly,  but  not  tightly  around  the  crown,  the  ends,  A,  A,  Fig.  839,  being 
placed  at  the  side  where  the  collar  will  be  joined  to  the  bridge  and  united 
with  hard  solder.  The  collar  is  readjusted  on  the  crown,  and  the  part 
at  B,  Fig.  840,  bent  down  over  the  occlusal  surface.  On  the  outside  of  the 
collar  a  slightly  narrower  strip  of  clasp  gold,  gage  No.  30,  is  adjusted  in 
the  position  shown  at  the  line  C,  then  removed,  and  the  joint,  which 
had  best  be  located  at  the  point  C,  soldered.  It  is  next  readjusted  on  the 
gold  collar,  removed  with  it,  and  soldered  to  it.  The  collar  can  be 
invested  for  this  purpose,  or  the  soldering  done  by  holding  it  in  a 
Bunsen  flame  and  placing  small  pieces  of  solder  in  position  in  the  seam. 
Only  enough  solder  should  be  used  to  unite  the  parts,  any  excess  being 


Fig.  841.  Fig.  842.  Fig.  843. 

carefully  avoided.  Painting  the  inner  surface  of  the  collar  with  rouge 
will  prevent  the  solder  flowing  there. 

The  collar  section  of  the  removable  cap  is  then  trimmed  smooth. 
The  flap  section  at  B  can  be  adapted  to  the  occlusal  surface  of  the  gold 
crown  and  reinforced  with  solder,  or  preferably  after  the  collar  section 
has  been  united  to  the  bridge,  and  its  relative  position  on  the  fixed  gold 
crown  in  the  mouth  is  accurately  determined.  Fig.  841  shows  the 
gold  crown  with  the  finished  removable  partial  gold  cap. 

Flanged  Collar  Attachment.^ — Fig.  842  shows  another  form  of 
removable  partial  cap.  In  this  the  entire  edge  of  the  collar  is  bent  over 
on  the  occlusal  surface  of  the  crown  and  thereby  supported  in  position. 

This  form  of  collar  is  made  entirely  of  clasp  gold,  gage  No.  28  for 
molars  and  No.  29  or  30  for  bicuspids.  The  process  is  as  follows:  An 
accurately  fitting  collar  is  first  made.  The  collar  is  then,  by  tapping 
with  a  small  horn  or  copper  hammer,  aided  by  frequent  annealings, 
shaped  on  the  gold  crown  or  a  die  of  the  tooth.  The  flange  section 
can  be  slightly  thinned  with  a  small  carborundum  wheel,  and  tapped 


402 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


to  position  over  the  edge  of  the  occlusal  surface.  To  shape  the  collar 
over  the  gold  crown,  the  crown  should  be  first  filled  with  fusible  metal 
as  previously  described. 

Lug  Collar  Support.— Fig.  843  illustrates  a  form  in  which  a  straight- 
sided  removable  collar  is  maintained  in  position  by  a  lug  on  the  side 
of  a  gold  crown.  Trimming  the  lug  or  edge  of  the  collar  will  at  any 
time  permit  the  denture  to  press  more  forcibly  on  the  tissues. 

The  Split-bar  Attachment 

This  attachment  is  used  as  a  retentive  abutment.  Its  merit  is  that 
it  does  not  require  paralleling  of  the  sides  or  canals  of  the  abutment 
teeth.     The  roots  consequently  are  not  weakened  by  reaming  as  in  the 


Pig.  846. 


Pig.   845. — B,   Position  box  is  to 
occupy;  P,  porcelain  facing. 


use  of  tubes  with  split  posts,  as  no  space  is  required  within  the  root  for 
this  attachment. 

The  split-bar  attachment  consists  of  a  flat  spring  bar,  as  shown  at 
A,  Fig.  844,  with  a  lug  B,  on  the  lingual  side.  This  bar  and  lug  fit 
into  a  socket  termed  a  box,  C,  embedded  in  the  gold  of  a  crown  or  an 
inlay.  By  means  of  the  slit  the  bar  is  expanded  and  tightened  in  the 
box. 

For  porcelain-faced  crowns  the  bar  is  placed  back  of  the  facing,  and 
for  all-gold  bicuspids  and  molars  toward  the  lingual  side.  Both  styles 
must  be  so  formed  as  to  furnish  ample  space  for  the  box  that  carries 
the  split  bar.  This  consequently  requires  the  natural  crown  to  be 
removed  for  porcelain-faced  crowns,  and  either  considerably  or  entirely 
removed  for  all-gold  crowns. 

Construction.- — For  a  porcelain-faced  crown  the  root  is  capped, 
with  a  post  in  the  canal.     A  detachable  porcelain  facing  that  allows 


REMOVABLE  BRIDGE-WORK  403 

room  for  the  box  is  ground  to  position  on  the  cap  and  attached  with  wax. 
A  removable  matrix  of  plaster  is  placed  on  the  labial  side  of  the  facing 
and  crown,  as  shown  in  Fig.  845.  The  facing  is  then  removed,  backed, 
replaced  in  position,  and  the  backing  attached  to  the  floor  of  the  cap 
with  a  particle  of  hard  wax. 

For  all-gold  bicuspids  and  molars  the  natural  crown  is  prepared 
with  a  step  on  the  Ungual  side,  as  shown  in  section  at  A,  Fig.  846.  A 
gold  collar  is  made  and  a  floor  of  thin  platinum  is  added,  as  seen  at  B. 
An  occlusal  cusp-cap  that  will  cover  the  buccal  section  is  next  added, 
as  shown  at  C,  leaving  space  for  the  box. 

The  Split  Bar. — ^The  split  bar  is  made  of  iridio-platinum  gold 
(clasp  gold)  or  iridio-platinum  plate,  by  evenly  doubling  on  itself  a 
piece  of  the  plate,  gage  22,  about  one  and  one-quarter  inches  long  and 
three-eighths  inch  wide.  The  two  ends  of  the  plate  are  first  brought 
together  the  same  as  in  the  construction  of  a  split  post,  and  then 
gradually  at  the  sides,  frequently  annealing.  When  the  sides  touch  they 
are  brought  in  close  contact  by  swaging  in  a  No.  2.  s wager.  The 
split  bar  then  assumes  the  thickness  of  gage  16  (Fig.  847). 


Fig.  847.  Fig.  848.  Fig.  849.  Fig.  850. 

The  lug  is  made  of  a  V-shaped  piece  of  plate,  gage  No.  30,  flattened 
in  the  swager.  The  lug  should  be  placed  a  little  distance  from  the 
edge  of  the  bar,  as  shown  in  Fig.  848,  and  attached  with  hard  solder. 
A  very  small  quantity  of  solder  should  be  used  and  antifiux  or  rouge 
placed  along  the  slit  of  the  bar  to  prevent  the  solder  accidentally 
flowing  into  it.  The  edges  of  the  lug  and  bar  are  then  trimmed  even, 
as  shown  in  Fig.  849. 

The  Box. — The  box  is  made  of  platinum  plate  gage  37  to  38  by 
looping  the  plate  around  the  closed  end  of  the  bar,  adapting  it  uniformly 
to  its  surface  and  then  trimming  it  even  with  the  edge  of  the  other  end 
of  the  bar  and  the  edge  toward  the  alveolus.  A  floor  is  added  to  the 
box  by  fitting  over  the  bottom  and  the  open  end  a  strip  of  the  platinum 
that  will  a  little  more  than  cover  the  edges,  attaching  it  with  wax  to 
the  sides.  The  bar  is  removed,  the  box  invested  and  soldered  with  pure 
gold.     The  surplus  edge  of  the  floor  is  then  removed.  Fig.  850. 

In  some  cases  when  conditions  suggest  it,  the  bar  can  be  placed  in 
either  the  center  of  the  approximal  side  of  a  crown  as  shown  at  A  and 
B,  Fig.  851,  or  at  an  angle  as  seen  at  C.     When  a  bar  is  placed  in  an 


404 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


inlay,  the  pulp  must  usually  be  removed,  to  permit  the  inlay  to  be 
securely  anchored. 

Paralleling  the  Box. — ^The  box  is  next  mounted  on  a  mandrel  and 
paralleled  in  proper  position  on  the  crown  to  any  other  abutment 
present.  The  alignment  of  the  bar  must  be  such  as  will  favor  the 
insertion  of  the  point  of  the  lug,  as  the  sides  of  the  lug  will  then  guide 


the  bar  to  position  in  the  box  (Fig.  852).  The  box  is  attached  with 
hard  wai  melted  with  a  hot  spatula  between  it  and  the  crown.  The 
wax  is  chilled,  the  mandrel  lifted  out  of  the  box,  the  crown  removed 
from  the  model,  and  shaped  and  contoured  with  ordinary  wax  to  the 
required  form.  If  a  porcelain  facing  is  present,  it  should  be  removed. 
The  crown  is  then  ready  for  investment. 

To  aid  in  holding  the  box  securely  in  position  in 
the  investment  during  the  soldering,  a  flat  piece  of 
graphite  with  a  long  shank  that  easily  fits  into  the 
box,  should  be  used.     The  box  should  be  filled  with 
a  very  thin  mixture  of  the  invest- 
ment material  and  the  graphite 
immediately     carefully     inserted 
and  the  shank  embedded  in  the 
investment. 

The  soldering  of  the  box  to  the 
crown  should  be  done  first  with  as 
hard  a  solder  as  possible  and  then 
the  contouring  with  lower  grades. 
Apply  a  slight  surplus  for  finish- 
ing. Soldering  is  preferred  to 
casting,  as  the  contraction  that 
occurs  by  the  latter  method  interferes  with  the  fit  of  the  bar  in  the 
box.  When  soldered,  the  excess  of  the  box  at  the  occlusal  edge  is  re- 
moved and  the  crown  trimmed  and  polished. 

The  split  bar  is  next  fitted  into  the  box.  Some  trimming  is  usually 
necessary  to  make  allowance  for  slight  changes  resulting  from  the 
manipulation  of  the  box  and  soldering  (Fig.  853). 


Fig.  852. 


Fig.  853. 


REMOVABLE  BRIDGE-WORK 


405 


The  Shield. — This  consists  in  the  placing  of  platinum  plate  pene- 
trated by  and  attached  to  the  split  bar,  against  the  approximal  surface 
of  the  crown.  In  the  construction  it  acts  as  an  approximal  surface 
for  the  adjoining  bridge-tooth  (dummy)  and  forms  a  dividing  line  in 
uniting  the  bar  to  the  bridge.  It  is  made  of  a  piece  of  platinum  plate, 
gage  No.  38,  about  three-sixteenths  inch  wide  and  one-fourth  inch  long 
(Fig.  854).  The  contour  of  the  crown,  approximal  to  the  split  bar  is 
beveled  slightly  to  the  line  of  the  insertion  and  removal  of  the  bar.     The 


Fig.  854. 


Pig.  855. 


Fig.  8:56. 


platinum  plate  is  perforated  to  admit  the  split  bar,  and  adapted  to  the 
side  of  the  crown  with  the  split  bar  in  position  in  the  box  (Fig.  855). 
The  platinum  attached  to  the  split  bar  with  wax,  split  bar  and  platinum 
are  removed  and  invested,  as  shown  in  Fig.  856,  and  united  with  hard 
solder.  At  the  same  time  solder  is  flowed  into  the  slit  between  the 
exposed  ends  of  the  split  bar,  to  unite  them  and  thus  permit  the  split 
bar  to  be  shortened  without  separating  the  bars,  as  they  are  only 
united  at  the  end  where  the  strip  was  bent. 


M         I 


Fig.  857.  Fig.  858.  Fig.  859. 

Fig.   858. — A,  shows  the  box  with  hole  for  pin  in  inlay;  B,  bar  and  pin. 

Fig.  857  shows  another  style  of  split-bar  attachment.  It  differs 
from  the  form  preceding  in  that  the  lug  is  made  of  solid  or  split  round 
wire.  The  construction  is:  The  bar  and  lug  are  made  of  clasp  gold. 
A  piece  of  clasp  gold  plate,  gage  No.  22  or  23,  js  doubled  to  form  the 
split  bar.  For  the  lug  a  solid  or  split  wire  is  fitted  to  a  hole  formed  in 
the  end  of  the  slot,  in  the  inlay  or  gold  crown  (A,  Fig.  858).  The  split 
bar  is  fitted  to  rest  on  the  bottom  of  the  slot,  its  extended  end  is  sold- 
ered in  a  groove  made  in  the  wire  to  receive  it  (B).  When  a  split 
wire  is  used  to  form  the  lug,  its  united  end  should  be  extended  from  the 


406  CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 

split  bar  far  enough  to  retain  it  in  position  in  the  investment  while 
being  soldered  (Fig.  859).  A  very  thin  sheet  of  mica  inserted  in  the 
slit  of  the  wire  and  bar  will  prevent  invasion  of  the  solder  (M,  Fig.  859). 
The  mica  can  be  removed  later  with  hydrofluoric  acid  and  the  parts 
pinched  together.  The  box  to  the  split  bar  is  soldered  in  the  inlay  or 
crown,  holding  the  box  in  position  while  being  soldered  by  a  piece 
of  carbon  fitted  into  it,  with  the  end  extended  into  the  investment. 
I  This  form  of  split  bar  is  suggested  as  suitable  for  a  shallow  box  ap- 
plied to  an  inlay  in  a  tooth  with  a  vital  pulp.  The  split  wire  or  lug 
is  more  retentive  than  the  solid  one.  Fig.  860  shows  a  split  bar  and 
lug  in  position  in  an  inlay  in  an  inferior  molar.    . 

Winged  Lug  Attachment. — ^This  is  simple  in  construction  and  appli- 
cation. It  is  made  by  doubling  on  itself  a  strip  of  clasp  gold  gage  22, 
clamping  it  in  a  vise  and  bending  the  extended  ends  outward  as  shown 
in  Fig.  861 .  A  piece  of  thin  mica  is  placed  in  the  slit  as  far  as  S,  and  the 
end  of  the  shank  is  soldered  together,  using  solder  filings  or  an  atom  of 


Fig.  860.  Fig.  861.  Pig.  862.  Fig.  863. 

hard  solder.  A  box  is  made  of  platinum,  gage  No.  40,  as  illustrated 
at  B.  The  corners  and  edges  of  the  wings  at  C  C  are  slightly  rounded. 
The  box  is  either  inserted  in  the  wax  model  of  the  inlay  and  embedded 
in  the  casting,  or  soldered  in  a  slot  provided  for  it  in  the  inlay.  Fig. 
862  shows  this  attachment  in  an  inlay  in  a  molar.  By  slightly  expand- 
ing the  center  or  by  bending  the  wings,  the  friction  is  increased.  As 
this  attachment  is  flat  and  small  in  size,  it  may  be  used  when  proximity 
to  the  pulp  limits  the  available  space. 

To  prevent  invasion  of  food  into  seams  of  the  attachment  in  masti- 
cation, an  oval-shaped  plate  may  be  placed  over  the  flanges  made  of 
platinum,  gage  38,  or  22-carat  gold,  gage  30,  as  shown  at  C,  Fig.  863. 
The  plate  is  united  to  the  bridge  and  flanges  and  reinforced  with  solder. 
A  thin  sheet  of  mica  placed  between  the  plate  and  the  wings  of  the 
flanges  will  obstruct  the  solder  at  that  point  if  it  is  desirable  to  leave 
the  wings  free. 

Dovetail  Flange  and  Split-post  Attachment. — This  attachment  is 
shown  on  the  side  of  a  gold  crown  in  Fig.  864.     It  consists  of  a  dove- 


REMOVABLE  BRIDGE-WORK 


407 


tail  flange  that  fits  into  a  socket  (B)  in  the  adjoining  bridge  tooth. 
A  split  post  (C)  fits  in  a  tube  in  the  dovetail  flange.  The  form  of  the 
flange  locks  the  bridge  tooth  and  consequently  the  end  of  the  bridge  to 
the  gold  crown,  while  the  split  post  secures  the  dove-tail  flange  in  posi- 
tion. The  dovetail  form  of  the  flange  relieves  the  split  post  of  lateral 
stress. 

The  dovetail  socket  with  the  tube  hole  (D)  is  first  made  by  shaping 
a  wax  model  of  the  form  of  the  dovetail  flange,  around  the  tube,  in- 
vesting and  casting.  It  can  also  be  made  by  filing  a  piece  of  fusible 
metal  to  the  form  and  size  of  the  dovetail  flange,  then  shaping  a  thin 
piece  of  platinum  plate  over  it,  placing  the  tube  supported  with  wax 
in  position  in  the  shaped  plate,  investing,  melting  out  the  wax,  and  either 
by  soldering  or  the  casting  process,  filling  in  the  space  between  the  tube 
and  the  plate  with  coin  gold. 


Fig.  865. 


Fig.  866. 


The  split  post  (E)  is  next  fitted  in  the  tube.  The  point  of  the  post  is 
best  extended  at  least  one-sixteenth  inch  through  the  end  of  the  tube. 
The  flange  is  next  soldered  to  the  crown,  a  platinum  box  formed  around 
the  flange,  the  post  soldered  in  the  box,  and  post  and  box  soldered  in 
position  in  the  bridge  tooth.  Both  flange  and  post  must  be  aligned  with 
the  other  abutment.  This  attachment  is  of  a  design  suitable  to  apply 
to  a  gold  crown  on  a  tooth  with  a  vital  pulp. 

Solid  Post  and  Tube  Attachment. — This  consists  in  the  use  of  a  solid 
post  of  clasp  gold,  gage  15  to  17,  instead  of  a  split  post.  Fig.  865  shows 
the  attachment  applied  in  an  inferior  bicuspid  gold  crown.  It  can  be 
advantageously  used  in  roots  too  small,  or  too  long  and  narrow  to 
properly  receive  a  tube  and  split  post.  In  the  use  of  a  soHd  wire  post  a 
short  slit  may  be  cut  in  the  extreme  point  with  a  very  thin  saw-edged  ■ 
separating  strip,  as  shown  in  Fig.  866.  The  slit  point  is  then  pinched 
together  and  burnished.  By  slightly  opening  the  slit,  or  slightly  bend- 
ing the  post  at  any  time,  friction  is  created. 


4o8  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Comparative  Values  of  the  Several  Forms  of  Attachments 

The  form  of  attachment  used,  especially  the  retentive,  constitutes 
an  all-important  factor,  for  on  it  depends  the  treatment  of  teeth  or 
roots  selected  as  abutments.  At  the  present  period  of  development  in 
bridge-work  art,  greater  efforts  are  being  made  than  in  the  past  to 
conserve  pulps  and  to  avoid  the  mutilation  of  the  coronal  sections  of 
natural  teeth  used  as  abutments.  This  latter  is  permissible  in  removable 
bridge  dentures  to  an  extent  not  allowable  in  the  fixed  forms.  In 
accordance  therewith  a  knowledge  of  the  various  forms  of  attachments 
in  use  and  a  study  of  their  practical  values  in  different  positions  and 
under  various  conditions  is  essential  in  what  must  be  considered  at  the 
present  time  as  the  most  approved  construction  in  removable  bridge 
denture  operations.  An  impartial  discussion  of  the  relative  values  of 
the  several  removable  bridge  attachments  analytically  considered 
respecting  application  and  construction  is  here  given. 

Retentive  Attachments 

Tube  and  Split-post  Attachment. — This  is  one  of  the  most  reliable 
of  all  attachments  for  retentive  power.  Its  greater  value,  which  is 
proportioned  to  the  length  and  size  of  the  spUt  post,  is  attributable  to 
the  character  of  its  construction  and  to  the  greater  amount  of  friction 
obtained  in  a  given  space  compared  with  that  procured  by  other  means. 

In  the  application  of  this  means  of  attachment  to  a  central  or  cuspid 
the  root-canal  should  not  be  excessively  reamed  in  paralleling  the  tube 
to  other  abutments.  The  other  abutment  or  abutments  instead  should 
be  paralleled  to  the  central  or  cuspid  by  some  permissible  method,  such 
as  an  inlay,  a  tube  and  split  post  in  a  molar,  or  a  tube  and  split  post  in  a 
lug  on  the  mesial  side  of  a  posterior  gold  crown.  Either  of  these 
methods  allows  setting  the  tube  and  post  at  the  required  angle. 

The  tube  and  spht  post  inserted  in  a  telescope  crown  is  classed 
as  one  of  the  most  reliable  of  all  forms  of  attachments. 

Tube  and  Split-post  Anterior  Crowns 

The  amount  of  retentive  power  of  this  form  of  abutment  is  depend- 
ent on  the  friction  of  the  post  in  the  tube,  as  the  half-collar  only  tends  to 
steady  the  crown.  The  retentive  power  of  such  an  abutment  therefore 
is  proportionate  to  the  gage  and  length  of  the  tube  and  split  post. 

Split -bar  Attachments 

This  form  is  seldom  used  except  in  a  pulpless  tooth  employed  as  a 
retentive  abutment,  owing  to  lack  of  space.     It  possesses  the  advantage 


REMOVABLE  BRIDGE-WORK  409 

over  a  tube  and  split  post,  in  that  it  can  be  set  in  a  tipped  tooth  or  crown 
at  any  angle  necessary  to  have  it  move  in  a  vertical  direction  or  parallel 
to  another  abutment.  In  its  application,  while  the  root  of  the  tooth 
is  left  intact,  the  coronal  section  will  be  so  weakened  that  a  gold  crown 
must  generally  be  substituted  to  receive  it.  Again,  split-bar  attach- 
ments compared  to  other  styles  of  attachments  require  considerable 
skill  and  practice  for  their  successful  employment.  A  split  bar  to 
support  an  adjoining  single  dummy  can  occasionally  be  inserted  in  a 
tooth  with  a  vital  pulp  which  has  become  considerably  calcified  owing  to 
the  presence  of  a  large  filling.  At  the  present  time  in  a  case  of  this 
class  a  saddle  bridge  with  either  a  rolled  gold,  a  wire,  or  a  cast  clasp 
with  a  lug  is  preferably  employed. 

Retentive  Inlay  Attachments 

As  the  retentive  power  of  the  inlay  attachment  is  dependent  chiefly 
on  the  friction  of  the  split  post  in  the  tube  inserted  in  the  inlay,  as  a 
retaining  abutment  it  may  be  classed  as  equal  or  next  to  the  tube  and 
split-post  crown.  It  admits  of  considerable  deviation  from  the  vertical 
in  paralleling  other  abutments  when  inserted  in  molars  but  not  in 
centrals,  cuspids  or  bicuspids. 

Other  Forms  of  Retentive  Attachments. — The  respective  merits  of 
clasps  with  lugs  and  other  forms  of  retentive  attachments  are  stated  in 
connection  with  the  description  of  their  construction. 

Manufactured  Retentive  Attachments. — These  are  described  in  Part 
V,  Chapter  VII.  They  furnish  an  additional  variety  of  forms  of 
attachments. 

Supporting  Attachments 

Telescope  Crown. — This  form  should  properly  be  classed  as  a  support- 
ing abutment,  as  it  cannot  always  be  relied  on  as  retentive,  especially 
on  a  superior  molar  or  bicuspid.  On  the  mandible  enough  friction 
may  be  obtained  to  retain  it  when  applied  to  a  small  bridge  extending 
from  the  first  bicuspid  to  the  second  molar  if  the  inner  cusps  are  long 
and  only  slightly  cone-shape  in  form.  A  telescope  crown  usually  is 
best  applied  as  a  supporting  abutment  in  combination  with  one  that  is 
retentive.  When  the  axis  of  a  tooth  is  greatly  out  of  line  the  use  of  a 
telescope  crown  is  contraindicated  in  favor  of  a  more  suitable  form  of 
attachment. 

Supporting  Lug  Attachment 

A  lug  extended  from  a  dummy  to  rest  on  the  lingual  surface  of  an 
adjoining  central  or  cuspid,  resists  stress  in  a  la  bio- vertical  direction; 


4IO  CROWN-,  BRIDGE  ,  AND  PORCELAIN  WORK 

if  it  is  inserted  in  a  socket  in  an  inlay  or  filling,  the  resistance 
effected  is  more  vertical.  A  lug  resting  on  the  occlusal  surface  of  a 
bicuspid  or  molar  resists  stress  only  in  a  vertical  direction,  but  when 
inserted  in  a  socket  in  an  inlay  or  gold  crown  it  also  acts  laterally. 
When  the  socket  and  lug  are  oval  or  dovetail  shaped  in  form,  addi- 
tional resistance  in  either  a  distal  or  mesial  direction  is  obtained.  Such 
a  form  of  lug  in  combination  with  a  clasp  usually  constitutes  a  reliable 
retentive  attachment  for  a  saddle  denture. 


CHAPTER  II 
CONSTRUCTION  OF  REMOVABLE  BRIDGE-WORK 

METHOD     OF    CONSTRUCTION THE     PARALLELING     STAPLE REMOVABLE 

BRIDGE  EXTENDING  ON  BOTH  SIDES  OF  THE  MOUTH — CONSTRUC- 
TION  DIVERSITY  OF  CONSTRUCTIVE  DETAILS — USE  OF  PARALLEL- 
ING  INSTRUMENTS THE    CHAYES    PARALLELOMETER 

Method  of  Construction 

1.  Determine  the  most  suitable  teeth  and  roots  to  use  as  abutments 
by  examination  of  the  case  in  the  mouth,  and  study  of  plaster  models  of 
the  same,  as  described  in  the  preceding  chapter. 

2.  Have  radiographs  taken  of  the  teeth  or  roots  selected  as  abut- 
ments, to  positively  determine  their  suitability  and  also  as  a  guide  in 
their  treatment. 

3.  Take  radiographs  of  all  teeth  and  roots  to  be  used  as  abut- 
ments, perform  such  necessary  preparatory  treatment  of  teeth  and 
roots  as  is  required,  and  shape  coronal  sections  and  crevices  properly. 
Guided  by  the  eye  and  study  of  the  model  and  radiographs  of  the 
roots,  ream  and  parallel  the  root-canals  that  are  to  receive  the  tubes, 
and  fit  in  each  of  them  the  intended  tubes  mounted  on  steel  or  brass 
wire  mandrels.  Brass  mandrels  can  be  made  of  straight  brass  wire, 
gage  No.  12,  placed  in  a  chuck  and  turned  on  a  lathe  to  the  required 
size.  The  mandrels  should  be  of  a  length  that  will  permit  their 
insertion  in  proper  position  and  the  taking  of  an  impression. 
Encircle  each  tube  on  its  mandrel  with  a  mark  to  show  how 
far  it  enters  the  root  or  tooth.  In  reaming  canals  for  tubes  the  rule 
to  follow  is:  ream  the  larger  canal  to  the  line  of  the  smaller  as  the  smaller 
allows  the  least  lateral  reaming,  whereas  for  instance  a  molar  permits 
considerable  lateral  placing  of  a  tube. 

In  paralleling  canals  to  place  the  tubes,  it  will  be  found  necessary 
in  many  cases  to  ream  one  or  more  of  the  roots  considerably  away  from 
the  central  section  or  line  of  the  pulp-canal,  using  the  Peeso  reamers  (Fig. 
867).  Such  reaming,  if  done  at  the  orifice  of  the  canal  in  the  case 
shown  in  Fig.  868,  will  frequently  leave  but  a  small  quantity  of  tooth 
structure  at  one  side,  as  illustrated  in  the  diverging  lines  of  the  canals. 
The  reaming  that  would  be  necessary  to  so  parallel  if  confined  to  one 

411 


412 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


root  is  shown  in  Fig.  869.  To  avoid  weakening  the  root  at  the  point 
A  by  this  excessive  reaming,  the  Hne  of  the  space  for  the  tubes  is 
carried  a  Httle  to  one  side  in  each  canal  and  the  amount  of  necessary 
reaming  at  the  orifices  of  the  canals  is  proportioned  between  the  two 


,1     I J    S 


U 

Fig.  867. 


Fig.  868. 


A 


Fig.  869. 

roots,  as  shown  in  Fig.  870.  In  reaming  canals  of  abutments  on  oppo- 
site sides  of  the  mouth,  the  relationship  bucco-lingually,  as  well  as 
laterally,  is  also  to  be  considered. 

In  the  construction  of  removable  bridge-work  the  abutment  roots 
and  crowns  that  carry  collar  attachments  require  to  be  shaped  parallel 


CONST  RUCTION  OF  REMOVABLE  BRIDGE-WORK  413 

to  each  other,  also  to  the  line  of  attachments,  such  as  tubes  and  split 
posts  and  all  forms  of  attachments  that  directly  enter  abutments. 

The  typical  case  used  in  describing  fixed  bridge-work  will  be  utilized 
to  describe  the  construction  of  removable  bridge-work  (Fig.  871).  A 
tube  and  spht-post  crown  with  a  porcelain  facing  will  be  used  on  the 
cuspid  and  a  telescope  crown  with  split  post  on  the  molar.     A  No.  4 


Fig.  870. 

tube  is  indicated  for  the  cuspid  and  a  No.  5  tube  for  the  molar.  In 
accordance  with_,the  methods  described,  the  cuspid  root  is  first  reamed 
for  the  tube  and  then  such  reaming  as  is  necessarily  indicated  by  the 
eye  in  the  molar  to  parallel  the  molar  tube  to  the  one  in  the  cuspid. 
The  tubes  are  next  encircled  with  a  mark  to  indicate  their  depth  in 
the  canal. 


Fig.  871. 


The  abutment  cuspid  root  and  molar  crown  are  next  trimmed  and 
shaped  for  gold  collars  so  that  the  collars  will  move  on  and  ofif  in  cor- 
responding parallel  lines  with  each  other  and  the  mandrels.  This 
is  done  first  by  paralleling  the  sides  of  the  abutments  and  then  slightly 
tapering  them  in  the  occlusal  direction  (Fig.  872).     Next  make  the 


414 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


gold  collars.    Leave  each  collar  a  little  longer  than  is  required  so  thai 
they  can  be  more  easily  removed  in  the  impression  (Fig.  873). 

Place  the  collars  on  the  cuspid  root  and  molar  crown  and  insert 
the  tubes  mounted  on  the  mandrels  in  the  same  previously  paralleled 


Fig.  872. 

position  in  the  canals  and  secure  the  tubes  in  the  collars  with  wax 
(Fig.  874).  Take  a  plaster  impression,  removing  the  collars  with  the 
tubes  on  the  mandrels.     Varnish  the  surface  of  the  plaster  impression 


Fig.  873. 

and  outer  surface  of  the  tubes,  veneer  the  cavo-surface  of  the  caps  with 
parafl&n  and  oil  the  several  parts.  Pack  around  the  portions  of  the 
tubes  that  are  to  enter  the  roots  amalgam  or  copper  oxyphosphate 


cement,  and  run  a  plaster  model.  When  the  amalgam  or  cement  is  set 
remove  the  plaster  impression  and  the  resultant  model  will  be  a  replica 
of  the  condition  in  the  mouth  with  the  tubes  on  the  mandrels  in  sockets 


CONSTRUCTION  OF  REMOVABLE  BRIDGE-WORK 


415 


of  amalgam  or  cement.  Remove  the  tubes  with  the  mandrels,  which 
is  facihtated  by  heating  both  mandrels  and  tubes,  and  boil  the  tubes  in 
nitric  acid  if  amalgam  was  used. 

The  Paralleling  Staple. — Select  straight  brass  rods  three  to  five 
inches  in  length  and  of  a  gage  such  as  will  fit,  or  by  turning  down  on  the 
lathe,  can  be  made  fit  the  tubes.  The  tubes  on  the  ends  of  the  brass 
rods  are  inserted  into  the  holes  on  the  model.  The  extending  ends  of 
the  brass  rods  will  plainly  indicate  any  divergence  from  parallel  lines 


Fig.  875. 

should  it  exist,  as  shown  in  Fig.  875.  Such  divergence  is  corrected  by 
removing  the  rods  and  tubes,  and  reaming  the  holes  in  the  model, 
guided  by  the  radiographs  of  the  roots  and  the  marks  made  on  the 
tubes  to  indicate  their  depth  in  the  roots. 

When  the  brass  rods  appear  to  be  properly  paralleled,  they  are 
tested  by  cementing  the  tubes  with  wax  on  the  model  and  removing 
and  replacing  the  rods,  either  by  holding  the  ends  together  or  cementing 
a  cross-bar  with  hard  wax.  When  there  are  three  or  more  rods,  two 
are  first  joined  together  and  then  the  others  connected  to  them. 


4i6 


CROWN-:  BRIDGE-,  AND  PORCELAIN-WORK 


The  rods  having  been  paralleled,  are  retained  in  relative  position 
with  two  cross-bars  cemented  with  wax  cement  (Fig.  876).  They  are 
next  removed  from  the  model,  each  rod  separately  seized  with  a  small 
hand-vise  or  phers  and  the  tube  pushed  off  with  an  instrument  (Fig. 
877).  The  rods  are  then  invested  and  the  wax  washed  out.  The  cross 
bars  will  fall  off  when  the  wax  is  removed.  Two  short  cross  bars  are 
then  fitted  in  between  the  brass  rods,  about  three-fourths  of  an  inch 
from  the  points  of  the  rods  as  they  enter,  and  one-fourth  of  an  inch 


Fig.  876. 


apart.  •  ^  The  investment  is  heated  and  the  rods  joined  together  with 
silver  solder.  The  excess  length  of  the  rods  is  then  cut  away,  leaving 
them  in  the  form  of  a  staple  projecting  about  three-eighths  of  an  inch 
beyond  the  line  of  the  molar  collar  so  that  when  later  placed  in  the 
mouth  the  staple  will  not  interfere  with  the  taking  of  the  impression 
(Fig.  878). 

The  tubes  are  placed  back  on  the  staple,  which  is  adjusted  on  the 
model  to  verify  its  accuracy,  and  at  the  same  time  the  collars  are 
carefully  examined  to  see  if  they  parallel  favorably  with  the  rods  of  the 


CONSTRUCTION  OF  REMOVABLE  BRIDGE-WORK 


417 


Staple,  as  the  rods  indicate  the  ultimate  position  of  the  tubes  (Fig.  879). 
If  the  collars  are  not  parallel  with  the  brass  staples  they  must  be  made 


Fig.  877. 


Fig.  878. 


Fig.  879. 


The  staple  and  tubes  are  next  adjusted  in  the  canals  in  the  mouth 
and  any  necessary  additional  reaming  done.  The  collars  are  removed 
from  the  model,  adjusted  in  the  mouth,  trimmed  to  the  surfaces  of  the 


27 


4i8 


CROWN-,  BRIDGE-,  AND  PORCELAIX-WORK 


abutment  roots  or  teeth  and  the  lloors  soldered  on.  Holes  for  the 
tubes  are  then  made  in  the  lloors  with  drills,  and  enlarged  with  burs 
sufficiently  to  allow  the  tubes  on  the  staple  to  move  in  and  out  freely 
without  touching  the  lloors. 

The  caps  are  placed  in  the  mouth,  the  staple  with  tubes  inserted, 
and  wax  pressed  in  the  opening  in  the  floor  around  the  tubes.  Plaster 
is  separately  placed  around  each  cap  abutment  and  all  removed.  The 
rod  of  each  staple  is  next  grasped  with  a  small  vise  and  by  pressing  on 
the  end  of  the  tube  with  a  small  chisel,  the  tube  and  cap  are  pushed  ofif 
the  rod.     The  tubes  and  caps  are  each  invested,  asbestos  packed  in  the 


Pig.  8So. 


Fig.  8Si. 


tubes  and  the  tubes  united  to  the  floors  with  20-carat  solder.  The 
solder  should  be  flowed  down  into  the  opening  around  the  tubes  in  the 
floors.  The  ends  of  the  tubes  are  next  trimmed  level  with  the  surface 
of  the  floors. 

An  outer  cap  with  a  split  post  is  next  made  for  the  cuspid  and  a 
telescoping  cap  with  a  split  post  for  the  molar,  with  the  slits  of  the  posts 
placed  in  a  linguo-buccal  direction  (Fig.  880). 

All  the  parts  are  placed  in  position  in  the  mouth  and  an  impression 
and  "bite"  taken  with  plaster  as  for  flxed  bridge-work  (see  Part  IV, 


h^ 


Fig.  883. 


Fig.  884. 


Fig.  885. 


Chapter  I).  The  cavo-surfaces  of  the  caps  and  the  outer  surfaces  of 
the  tubes  are  veneered  with  paraffin  and  models  are  made  and  mounted 
on  an  articulator.  The  occlusal  cusps  of  the  molar  and  the  porcelain 
facing  of  the  cuspid  are  added  in  accordance  with  the  antagonizing 
teeth  (Fig.  S81).  The  bridge  teeth  (dummies)  are  next  constructed  and 
united  to  the  outer  caps  of  the  abutment  crowns. 

In  removable  bridge-work,  if  a  saddle  is  not  used,  the  bases  of  the 
artificial  teeth  (dummies)  are  generally  made  to  rest  closely  on  the 
membrane  of  the  alveolar  ridge.  For  this  purpose  the  surface  of  the 
plaster  model  is  slightly  scraped  and  a  piece  of  platinum  foil  or  pure  gold 


CONSTRllCriON  OF  REMOV A  ni.l:  I'.KI DCEWORK 


419 


])lalc  adaplcd  ovc^r  ihe  surfjuc.  The  Ijuscs  of  I  Ik-  jjort  elain  facings  arc 
ground  with  a  nnrrow  V-sha[)C(i  space  aL  the  cervico-lahial  side,  and 
backed,  as  illustrated  in  Mg.  882.  This  space  is  to  be  fdled  with  gold  in 
the  soldering,  and  when  finished  appears  as  shown  in  I'"ig.  88;?.  The 
metallic  section  of  such  a  dummy  (an  be  made  entirely  of  gold  by  the 
casting  process  and  the  porcelain  facing  then  cemented  to  jjlace  (Fig. 
884),  as  described  in  relation  to  replaceable  incisor  facings  (\'\g.  885). 

Mg.  886  shows  the  completefl  removabh-  bridge. 

In  removable  bridge  construction,  the  contraction  of  gold  in  solder- 
ing must  be  more  carefully  considered  than  in  the  fixed  f(jrm,  as  the  align- 
ment of  the  parts,  especially  the  tubes  knd  split  posts,  is  easily  afYected. 
For  this  reason,  the  solrlering  should  be  done  in  sections  and  the  sections 
then  united  in  a  final  soldering  operation.  'I'he  dummies  should  be 
formed  first,  next  they  should  be  soldered  together,  and  thea united  to 
the  outer  caps  of  the  abutment  crowns.  In  the  tyjjical  case  shown  in 
Fig.  886,  the  bicusf)id  dummies  were  made  in  this  manner. 


■frn'"l"lnr„K 


I''ri..   ««6. 


In  the  construction  of  removable  bridge  work,  the  (  orrect  readjust- 
ment of  caps,  crowns  or  dummies  that  are  removed  from  the  moflel  can 
be  assured  by  the  use  of  a  r(;movable  f)laster  matrix. 

Removable  Bridge  Extending  on  Both  Sides  of  the  Mouth.  In  the 
case  illustrated  in  I''ig.  887,  the  tvVo  cuspid  roots,  right  second  molar  and 
left  first  molar  are  the  abutments.  Split  posts  and  tube  crowns  with 
'porcelain  facings  are  made  for  the  cuspids,  a  telescope  crown  with  split 
post  for  the  right  second  molar,  anrl  an  inlay  with  sf)lit  (K)st  for  the  left 
first  molar.  The  pulps  of  the  four  abutment  teeth  are  devitalized 
and  the  root-canals  filled.' 

Construction.  Ream  and  jjarallel  root-canals  to  receive  tubes  and 
fit  the  tubes  on  the  brass  rcKJs  int.o  them.  Trim  and  shaf^e  the  cusjjid 
roots  and  molar  so  that  caps  will  move  on  and  oil  in  line  with  one  an- 
other, parallel  with   the  brass  rods,  and  sfiajie  the  cjivity   in  the  Ic-ft 

'Same  as  case  shown  in  l''ij<.  561. 


420 


CROWI^-,  BRIDGE-,  AND  PORCELAIN-WORK 


first  molar  for  the  inlay  attachment,  as  described  in  Chapter  I.  If 
possible,  have  the  line  of  the  side  walls  of  the  inlay  cavity  parallel  with 
that  of  the  rods  and  sides  of  the  other  abutments,  so  that  the  inlay  can 
be  removed  with  them  when  an  impression  is  taken.  Next  make  the 
abutment  gold  collars  and  the  matrix  section — female  inlay — for  the 
inlay  attachment  in  the  molar  with  a  hole  for  the  tube. 


Fig.  887. 


Pig.  888. 

Place  the  gold  collars  on  the  abutments  and  the  gold  inlay  matrix 
in  the  cavity  of  the  molar  in  the  mouth,  and  insert  the  brass  rods  with 
the  tubes  in  the  canals,  surrounded  with  wax  packed  in  the  collars  and 
inlay  matrix  (Fig.  888),  and  take  an  impression  in  plaster,  removing  in 
the  impression  the  collars,  inlay  matrix  and  brass  rods  with  the  tubes. 

Veneer  cavo-surface  of  inlay  matrix  with  paraffin,  also  the  inside 
surface  of  the  caps,  varnish,  oil  and  make  a  model,  as  already  described. 


CONSTRUCTION  OF  REMOVABLE  BRIDGE-WORK 


421 


Next  form  a  paralleling  staple,  as  previously  described,  to  accurately 
parallel  the  several  tubes,  which  is  very  necessary  in  this  case.  Place 
the  tubes  for  the  canals  on  the  rods  of  the  staple,  and  examine  the  collars 
to  see  that  they  are  favorably  paralleled  with  the  tubes  on  both  sides  of 


Fig.  8i 


the  model  (Fig.  889).  Next  fit  the  tubes  mounted  on  the  staple  in  the 
root-canals  in  the  mouth,  then  remove.  Remove  collars  and  inlay 
matrix  from  the  model  and  adjust  them  in  the  mouth.     Trim  collars  and 


Fig.  890. 

add  floors.  Make  holes  in  floors  and  insert  the  tubes  mounted  on  the 
staple,  through  the  floors  and  matrix  (Fig.  890).  Press  wax  in  the  open- 
ings around  the  tubes  in  floors  and  inlay  matrix,  place  plaster  around  on 
each  and  remove  all  together  with  the  staple. 


422 


CROWX-,  BRIDGE-.  AXD  PORCELAIN -WORK 


Remove  separately  from  the  staple  all  the  tubes  with  the  caps, 
invest  them  separately  and  solder  the  tubes  to  the  floors.  Remove 
the  protruding  portions  of  all  the  tubes.  Outer  caps  with  split  posts  are 
next  made  for  the  cuspids,  the  telescoping  cap  with  split  post  for  the 
right  molar  and  the  male  inla}'  with  split  post  for  the  left  molar. 

An  ensemble  of  all  the  parts  is  then  made  in  the  mouth,  an  impres- 
sion and  "bite"  taken,  and  models  made  mounted  on  an  articulator. 
The  porcelain  facing  of  the  cuspids  and  the  occlusal  cusp  of  the  right 
molar  are  then  added  (Fig.  8qi). 

In  the  construction  of  the  bridge,  the  second  bicuspid  dummy  on 
the  left  side  is  securely  united  to  the  male  section  of  the  removable 
split-post  inlay  attachment.  In  a  case  where  the  conditions  do  not 
permit  the  inlay  attachment  to  be  removed  with  the  bridge  in  the  con- 
struction, it  is  united  after  the  remainder  of  the  bridge  is  formed,  in  a 


Fig.  891. 

separate  fitting  and  soldering  operation.  Fig.  892  shows  the  completed 
bridge. 

Diversity  of  Constructive  Details. — In  paralleling  the  canals  for 
the  tubes,  place  the  tubes  on  brass  rods  or  the  steel  mandrels  on  which 
they  were  formed,  and  with  them  parallel  the  tubes  in  the  mouth,  guided 
only  by  the  eye.  Each  mandrel  tube  and  cap  is  then  covered  with  plas- 
ter, removed,  the  mandrels  removed  from  the  tubes,  each  tube  and  cap 
separately  invested,  and  the  tube  soldered  to  the  cap. 

Detached-post  crowns,  Goslee  teeth  or  replaceable  porcelain  facings 
may  be  used  instead  of  the  ordinary  two-pin  porcelain  facings,  as  de- 
scribed in  tixed  bridge-work. 

Use  of  Paralleling  Instruments. — In  the  construction  of  a  removable 
bridge,  the  paralleling  of  the  abutments  and  tubes  is  simplified  and  the 
making  of  a  paralleling  staple  avoided,  by  the  use  of  a  paralleling 
instrument. 


CONSTRUCriOS  01'   REMOVABLE  BRIDGE-WORK 


423 


The  Weinstein  paralleling  device,  large  size,  illustrated  in  Fig.  893, 
and  small  size  in  Fig.  894,  consists  of  a  semicircular  flat  bar,  as  marked 


Fig.  893. 


in  each  illustration,  B  B,  with  round  holes  to  recieve  the  screws  S,S, 
that  fasten  the  cross  bars,  C  B,  when  they  are  positioned.     In  the  ends 


424 


CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 


of  these  cross-bars,  the  several  mandrels  to  gage  the  line  of  the  canals 
are  fastened  in  a  horizontal  position  by  the  end  screws,  E  S. 

In  practical  application  each  cross-bar,  C  B,  is  loosened  by  the  screw 
S,  which  allows  it  to  be  pushed  inwardly,  outwardly,  or  turned  to  the 
right  or  to  the  left,  as  indicated  by  the  dotted  lines  in  the  figures,  and 
then  fastened  by  the  screw  S  at  the  same  time  the  mandrel  is  positioned 
in  the  root-canal,  and  fastened  by  the  screw,  E  S.  Two,  three,  or  more 
canals  may  be  paralleled  together  at  the  same  time. 

This  instrument  may  be  used  for  a  double  purpose,  first  to  assist 
in  gaging  and  paralleling  the  canals  for  the  tubes,  using  mandrels  the 


Fig.  894. 

size  of  the  intended  tubes;  and  second  to  position  the  tubes,  by  re- 
placing the  large  mandrels  by  a  smaller  set  that  will  fit  into  and  carry 
the  tubes.  Plaster  is  placed  around  each  mandrel,  cap  and  tube.  When 
the  plaster  is  set,  they  are  removed  from  the  mouth.  Each  tube  and 
cap  is  next  separately  removed  from  the  mandrels,  invested,  and  united 
with  solder. 

The  Chayes  Parallelometer. — This  instrument  and  its  use  in  con- 
nection with  the  Chayes  attachments  is  described  in  Part  V,  Chapter 
VI.  The  ordinary  mandrels  may  be  used  with  this  instrument  to  paral- 
lel removable  bridge  tubes,  in  the  same  manner  as  with  the  set  that 
comes  with  the  instrument. 


CHAPTER  III 
THE  SPLIT-BAR  BRIDGE 

The  use  of  the  spHt  bar  instead  of  the  spUt  post,  will  be  de- 
scribed in  its  application  to  the  typical  case  shown  in  Fig.  895. 

The  cuspid  is  prepared  the  same  as  for  a  gold  collar  crown  with  a 
porcelain  facing  (A),  the  molar  with  a  step  on  the  lingual  side  to  form  a 
space  to  place  the  box  in  which  the  split  bar  fits  (B).     The  cuspid  root 


Fig.  895. 

and  molar  are  capped,  as  described  for  a  spHt-bar  attachment,  (Part 
V,  Chapter  I),  A  and  B,  Fig.  896.  An  impression  and  "bite"  are 
next  taken  with  the  abutment  caps  in  position.  The  cavo-surf  ace  of  the 
caps  is  veneered  with  parafl&n,  and  the  upper  impression  is  run.  When 
the  plaster  is  set,  the  articulating  model  is  made. 


Fig.   896. 

A  Steele  facing  is  ground  to  position  on  the  cuspid  cap  and  attached 
with  wax.  A  removable  matrix  of  plaster  is  placed  on  the  labial  side 
of  the  cuspid  facing  and  cap,  to  permit  the  removal  and  replacement  in 
position  of  either  during  the  construction  (A,  Fig.  897).  A  matrix 
should  also  be  placed  against  the  molar  cap  to  insure  correct  replace- 
ment (B).  The  cuspid  facing  is  removed  and  backed,  and  the  partial 
cusp-cap  is  added  to  the  molar  (Fig.  898). 

425 


426 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


To  parallel  the  boxes,  assemble  all  the  parts  in  position  on  the  model 
aiid  attach  the  cuspid  facing  and  backing  to  the  floor  of  the  cap  with  a 
particle  of  wax.     While  it  is  possible  to  parallel  the  boxes  the  one  to 


>1  I         ^       \:-'.'4 


Fig.  897. 


the  other,  guided  by  the  eye  or  by  using  flat  bars  of  brass  of  the  same 
gage  as  the  split  bar,  as  mandrels,  the  paralleling  is  best  done  with  a 
parallelometer,  by  soldering  the  brass  bars  to  brass  rods,  and  setting 
the  rods  in  the  mandrel  holes  (Fig.  899). 


In  the  typical  case,  Fig.  898,  the  box  is  attached  to  the  floor  of  the 
cap  of  the  cuspid  and  backing  with  hard  wax.     The  brass  bar  in  the 


Fig.  899. 

box  is  next  removed  by  carefully  loosening  the  screw  that  holds  the 
brass  rod  in  the  paralleling  tool  and  withdrawing  the  bar  out  of  the  box. 
A  carbon  of  the  same  size  as  the  flat  bar  is  then  inserted  in  the  box. 


THE  SPLIT-BAR  BRIDGE 


427 


The  box  to  the  molar  crown  may  then  be  set.     The  preferable  method  is 
to  first  complete  the  cuspid  crown,  readjust  it  on  the^model  and  set  the 


Fig.  900. 

box  to  the  molar  with  hard  wax,  insert  the  carbon  in  the  box,  invest, 
unite  with  solder  and  trim.     The  split  bars  are  next  fitted  into  the 


Pig.  901. 

boxes  and  the  shields  applied,  as  described  in  Part  V,  Chapter  I  (see 
Figs.  854  to  856),  and  shown  in  Fig.  900.  The  dummies  are  next  added 
and  the  bridge  completed,  as  shown  in  Fig.  901. 


CHAPTER  IV 

REMOVABLE  SADDLE  BRmGE-WORK 

CONSTRUCTION  OF  SADDLES — METHOD  OP  TAKING  IMPRESSIONS  POR 
SADDLES — THE  ARTICULATION — THE  BRIDGE  TEETH — ^CONSTRUCTION 
OF  PORCELAIN-FACED  SOLID  GOLD  DUMMIES  FOR  SADDLES — SOLID 
GOLD  TEETH  DUMMIES — \^ULCANITE  ATTACHMENT — EXTENSION 
SADDLE  BRIDGE — AN  ADJUSTABLE  SADDLE — ^VULCANITE  EXTENSION 
SADDLE 

A  dental  saddle  bridge  scientifically  defined  is  a  combination  of  a 
truss  and  pontoon  bridge.  The  supporting  crowns  act  as  the  truss 
abutments — ^substructure — and  the  saddle  the  superstructure — bearing 
on  the  ridge  as  the  pontoon. 

A  saddle  should  fully  cover  the  area  of  the  absorption  of  the  alveolar 
ridge  caused  by  the  loss  of  the  teeth  to  be  replaced,  and  when  permissi- 
ble should  extend  a  little  beyond  it.  In  removable  bridge- work  a 
saddle  is  not  open  to  the  same  objections  as  in  the  fixed  form.  The 
use  of  saddles,  in  the  construction  of  removable  bridge-work,  especially 
on  the  mandible,  is  gradually  becoming  the  preferred  method. 

A  saddle  of  the  proper  size  will  materially  aid  the  abutments  in 
sustaining  a  bridge  by  relieving  the  direct  and  lateral  stress  on  the 
abutments.  It  also  permits  restoration  of  the  contour  of  the  parts 
absorbed,  thus  avoiding  spaces  under  the  artificial  teeth. 

Construction  of  Saddles. — In  the  typical  case.  Fig.  88 1,  the  appli- 
cation of  a  saddle  under  the  bicuspids  will  be  described. 

The  abutment  crowns  are  placed  in  position  and  an  impression 
taken  of  the  pbrtion  of  the  alveolar  ridge  that  is  to  be  occupied  by  the 
saddle. 

In  the  construction  of  saddle  bridge-work,  interchangeable  facings 
or  detached-post  crowns,  are  preferably  used  on  the  porcelain-faced 
abutment  crowns,  as  the  porcelain  can  be  removed  during  soldering 
operations.  In  the  typical  case  in  hand,  an  interchangeable  porcelain 
facing  will  accordingly  be  used  on  the  cuspid. 

Methods  of  Taking  Impressions  for  Saddles. — A  plaster  impression 
is  the  most  reliable  and  most  used.  The  following  method  is  one  that 
will  depress  the  soft  parts  of  the  membrane  of  the  alveolar  ridge,  make 
an  allowance  for  the  movement  of  the  muscles  of  the  cheek  and  in  the 
case  of  a  lower  impression,  the  muscles  of  the  tongue.     A  wax  or  com- 

428 


REMOVABLE  SADDLE  BRIDGE-WORK 


429 


pound  impression  of  the  part  to  be  covered  by  the  saddle  is  first  taken 
in  a  small  impression  cup,  and  a  plaster  model  run.  The  part  to  be 
occupied  by  the  saddle  is  marked  on  the  model,  as  shown  at  A,  Fig.  902, 
and  the  surface  of  the  model  given  a  coat  of  sandarac  varnish.  When 
the  varnish  has  dried,  the  surface  is  wet  with  water,  and  upon  it  is  shaped 
a  piece  of  softened  compound  about  the  size  of  the  intended  saddle, 
and  extended  up  on  the  mesial  side  of  the  molar  crown  and  the  distal 
side  of  the  cuspid.  The  compound  is  then  chilled,  removed  from  the 
model  and  trimmed,  guided  by  readjustment  on  the  model,  so  that  it 
will  only  cover  the  portion  outlined  for  the  saddle,  less  about  one-eighth 
of  an  inch  at  the  buccal  side,  as  shown  at  B,  Fig.  903.  The  object  of 
this  reduction  of  the  area  for  the  saddle  is  to  give  the  muscles  that  much 
more  room  for  movement.  The  impression  compound  is  intended  as  a 
medium  to  carry  and  compress  the  plaster  on  the  central  portion  of  the 
ridge,  and  allow  it  to  press  out  at  the  side  and  take  the  form  of  that 
part  in  a  manner  that  will  leave  more  room  for  movement  of  the  muscles. 


Fig.  903. 

The  compound  having  been  trimmed  as  described,  the  surface  of 
the  impression  is  slightly  serrated.  The  plaster  is  then  mixed  to  the 
consistence  of  a  thick  cream,  the  compound  dipped  in  water,  the  surplus 
water  shaken  off,  and  the  surface  of  the  compound  evenly  covered  with 
the  plaster  inserted  and  pressed  to  position  in  the  mouth,  and  the  pa- 
tient instructed  to  instantly  contract  the  muscles  of  the  cheek  and  so 
hold  them  until  the  plaster  sets.  In  a  lower  impression  the  patient 
should  raise  the  tongue  and  so  hold  it.  This  gives  an  impression  of  the 
contracted  form  of  the  tissue  and  muscles,  that  allows  space  for  their 
movement,  which  aids  in  avoiding  irritation  for  want  of  room  when  the 
saddle  is  worn,  an  important  matter  from  a  practical  standpoint. 

The  impression  when  removed  is  varnished  and  oiled  and  a  plaster 
model  run  and  the  exact  size  of  the  saddle  is  marked  on  the  model. 
On  the  palatal  side  the  space  marked  should  entirely  cover  the  area  of 
absorption  of  the  alveolar  process.  The  surface  of  the  plaster  model 
should  be  scraped  at  the  edge  of  the  space  at  the  palatal  side  about  one- 
thirty-second  inch  in  depth  to  countersink  the  edge  of  the  saddle  and 
cause  it  to  slightly  indent  the  membrane. 


43°  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

The  saddle  is  made  with  a  turn-over  rounded  edge.  For  this  pur- 
pose a  wax  ridge  one-sixteenth  of  an  inch  high,  is  built  around  on  the 
model  at  the  line  marked  as  the  size  for  the  saddle,  as  illustrated  in 
Fig.  904  and  in  section  in  Fig.  905.  To  lessen  the  pressure  of  the  sad- 
dle on  the  gingival  margins  of  the  membrane  at  the  abutments,  that 
part  is  marked  on  the  model,  and  narrow  layers  of  thick  tin  foil  added 
until  a  thickness  represented  by  about  gage  No.  26  is  obtained,  as 
indicated  at  T  F,  Fig.  904. 

The  same  result  may  also  be  effected  by  scraping  the  same  area  in 
the  impression  around  the  abutments  before  running  the  plaster  model. 


Fig.  904. 

A  zinc  die  and  lead  counter-die  are  made  in  the  usual  manner.  To 
simplify  the  making  of  the  mold  for  the  casting,  trim  the  plaster  model 
and  cut  off  the  teeth  to  the  line  to  which  the  plate  will  extend. 

The  saddle  is  made  of  platinized  gold,  gage  No.  28  to  29,  or  platinum, 
gage  No.  32  to  33.  Platinum  is  the  metal  preferred  for  the  health  of 
the  membranes,  but  as  it  has  to  be  reinforced  with  22-carat  gold,  and 
the  difference  of  the  expansion  and  contraction  of  the  two  metals 
when  heated,  is  such  as  to  slightly  warp  the  saddle,  a  preference  is 
now  being  given  to  platinized  gold. 


Fig.  905.  Fig.  906. 

The  metal  plate  for  the  saddle  should  be  cut  enough  larger  to  allow 
for  the  turned-up  rim  and  provide  a  slight  surplus  for  trimming.  The 
plate  is  swaged  to  the  form  of  the  die  in  the  usual  manner  and  the 
turned-up  edge  is  trimmed  evenly  all  around.  The  under  side  of  the 
saddle  is  painted  with  rouge,  and  coin  or  22-carat  gold  is  flowed  evenly 
into  the  groove  of  the  turned-up  edge  and  on  the  adjacent  surface  of  the 
saddle,  to  reinforce  the  saddle  and  permit  a  rounded  form  to  be  given 
the  edge  later  on.  When  platinum  is  used  for  the  saddle,  a  film  of  pure 
gold  should  first  be  flowed  over  its  surface  before  the  coin  or  22-carat 
gold  is  applied.  The  surface  of  the  metal  is  smoothed  with  a  car- 
borundum wheel  and  the  edge  rounded,  as  shown  in  section  in  Fig.  906. 


REMOVABLE  SADDLE  BRIDGE-WORK  431 

The  saddle  is  next  cleaned  in  acid  and  again  swaged,  to  correct  any- 
warping  occasioned  by  the  gold  that  was  flowed  over  its  surface. 

When  a  cast  saddle  is  used,  a  correspondingly  shaped  ridge  of  wax  is 
placed  around  the  margins  of  the  wax  model  to  secure  an  oval  edge. 
In  both  swaged  and  cast  saddles,  the  metal  should  be  extended  around 
and  sHghtly  up  on  the  sides  of  the  abutments  approximal  to  the  saddle  to 
aid  in  retaining  it  in  correct  position  on  the  ridge  when  fitted  in  the 
mouth  and  to  facilitate  uniting  it  with  solder  to  the  abutments. 

f      1" 


Fig.  907. 

When  the  saddle  is  swaged,  it  is  fitted  in  the  mouth  and  note  is 
taken  whether  the  flanges  of  the  metal  extending  up  on  the  abutments 
press  on  them  in  such  manner  as  to  interfere  in  the  slightest  degree 
with  the  saddle  freely  taking  its  position  on  the  ridge. 

The  edge  of  the  saddle  when  fitted  against  the  molar  crown  should 
extend  from  the  mesial  side  slightly  around  on  the  buccal  and  lingual 
sides,  as  indicated  at  A  and  B,  Fig.  907,  in  all  about  one-third  the  cir- 
cumference of  the  cervix,  and  in  the  case  of  the  cuspid,  from  the  labio- 
distal  edge  of  the  partial  collar,  as  indicated  at  D,  Fig.  908,  and  well 
around  on  the  lingual  side,  to  the  point  marked  E.  Fig.  909  shows  the 
fitted  saddle  in  position. 


Fig.  909. 

In  all  forms  of  removable  saddle  or  plate  bridge-work,  when  the 
crowns  and  attachments  are  in  position  in  the  mouth,  the  plate  constitut- 
ing the  saddle  should  not  merely  rest  on  but  should  press  on  the  inter- 
vening alveolar  border,  to  better  afford  support.  Such  construction  is 
obtained  by  applying  a  suitable  amount  of  pressure  on  the  saddle  with 
the  abutment  crowns  in  the  mouth  and  taking  an  impression. 

In  taking  the  impression  in  the  case  shown  in  Fig.  909,  pressure  is 
exerted  on  the  saddle  with  the  finger,  and  plaster  applied  on  and  around 
the  abutments,  saddle  and  adjacent  parts.  The  finger  is  held  steadily 
until  the  plaster  sets  (Fig.  910). 


432 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Another  method  is  to  exert  pressure  on  the  saddle  with  an  instru- 
ment, and  apply  the  plaster  in  an  impression  tray  with  an  opening  in 


Fig.  910. 

the  bottom  to  accommodate  the  instrument,  as  shown  in  Fig.  911.  A 
little  compound  previously  melted  on  the  center  of  the  surface  of  the 
saddle  will  prevent  the  point  of  the  instrument  from  slipping  (Fig.  912). 


Pig.  911. 

The  model  made  will  show  the  abutments  and  saddle  in  position  as  in 
the  mouth. 

The  ends  of  the  bridge  are  next  waxed  to  the  outer  crowns.     To  pre- 
vent the  slightest  displacement  in  removal  or  investing,  a  piece  of  iron 


Pig.  912. 

wire,  about  gage  No.  15,  is  bent  to  rest  on  the  surface  of  the  saddle  with 
the  ends  extended  on  the  lingual  and  occlusal  surface  of  the  outer  or 


REMOVABLE  SADDLE  BRIDGE-WORK 


433 


removable  section  of  the  molars  and  cuspid  crowns,  as  shown  in  Fig. 
913.  The  wire  is  waxed  in  position  to  the  saddle  and  to  the 
removable  section  of  the  crowns  only,  with  hard  adhesive  wax. 
The  saddle  and  crowns  are  removed  from  the  model  and  the  inner  caps 
are  removed  from  the  outer  crowns.  When  the  crowns  waxed  in  position 
with  wax  cement  cannot  be  removed  without  displacement,  plaster 
should  be  applied.  This  is  often  necessary  when  a  model  is  made  with- 
out provision  for  the  removal  of  the  inner  caps  from  the  model.  The 
outer  crowns  with  the  saddle  are  invested.  The  investment  should 
extend  up  over  the  sides  of  the  saddle  to  retain  it  in  position  for  the 


Fig.  913. 

soldering.  If  a  replaceable  porcelain  facing  or  detached-post  crown 
has  been  used,  it  is  removed  from  the  outer  cap  and  the  vacancy  filled 
with  additional  investing  material.  The  invested  case  will  then  appear 
as  illustrated  in  Fig.  914.  The  soldering  is  preferably  done  with  21- 
carat  solder.  The  solder  should  be  first  drawn  into  the  seams  and  the 
parts  then  united  by  the  addition  of  sufficient  solder.  After  it  is  cooled 
and  cleaned  in  acid,  it  is  adjusted  on  the  model  with  the 
inner  caps  in  place.     If  any  slight  warping  has  occurred  through  con- 


PiG.  914. 

traction  of  the  solder,  it  can  generally  be  remedied  by  holding  the 
crowns  firmly  in  position  on  the  model  and  then  pressing  on  the  saddle. 
If  the  contraction  is  considerable,  the  end  at  which  it  occurred  must  be 
detached  from  the  cap,  the  warping  corrected  and  the  saddle  and  caps 
reinvested,  and  the  warped  end  again  soldered.  Contraction  can 
usually  be  controlled  by  investing  so  as  to  expose  and  solder  only  one 
end  of  a  saddle  at  the  time,  readjusting  on  the  model  and  then  again 
investing  and  soldering  the  other  end. 

28 


434  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

The  Articulation. — An  articulation  is  next  taken,  preferably  with 
plaster,  for  accuracy.  The  plaster  should  be  applied  so  as  to  include 
one  or  two  of  the  adjoining  teeth,  as  a  new  model  must  also  be  run,  for 
the  reason  that  the  plaster  articulation  will  seldom  allow  the  bridge  to 
fit  on  the  model  previously  used. 

The  plaster  is  mixed  moderately  thick  and  placed  over  the  saddle, 
also  the  abutment  crowns  and  one  or  two  of  the  adjoining  teeth,  and 
the  patient  directed  to  occlude  the  teeth.  It  is  well  to  carefully  ex- 
amine and  see  that  the  teeth  have  been  properly  occluded.  When  the 
impression  is  removed,  the  model  and  articulation  are  made  in  the 
usual  manner. 

The  Bridge  Teeth. — In  removable  all-gold  saddle  bridge- work, 
detached-post  crowns  or  English  tube  teeth  are  most  commonly  used 
on  the  saddle,  as  they  are  light  in  weight,  replaceable  in  case  of  fracture, 
and  more  artistic  in  appearance  than  porcelain  facings  with  gold  back- 
ings.    They  are  set  in  gold  sockets  soldered  to  the  saddle. 


Pig.  915.  Fig.  916.  Fig.  917. 

The  porcelain  crowns  selected  are  ground  to  articulate  and  their 
bases  to  conform  to  the  shape  of  the  saddle,  leaving  sufficient  interven- 
ing space  for  the  gold  bases  or  sockets.  They  are  then  beveled  around 
the  edge  of  the  cervical  section,  as  shown  in  Fig.  915,  to  make  room  for 
the  rim  of  the  gold  base.  The  gold  bases  are  formed  by  casting,  or  by 
swaging  pure  gold  gage  No.  35  or  36  (see  Part  III,  Chapter  XIV) . 
The  rim  of  each  socket  should  be  extended  up  on  the  porcelain  suffi- 
ciently to  allow  for  soldering  and  finishing. 

In  the  formation  of  cast  bases  for  porcelain  teeth,  an  allowance 
should  be  made  for  the  shrinkage  of  the  metal.  To  this  end  the  bases 
should  be  varnished  with  collodion  and  vaselined  as  described  in  Part 
III,  Chapter  XIV,  or  a  piece  of  tin  foil,  .005  to  .009  of  an  inch  in  thickness 
should  first  be  adapted  or  swaged  over  the  base  of  the  porcelain  tooth. 
The  thickness  of  the  foil  should  be  increased  in  proportion  to  the  size 
of  the  base.  The  surface  of  the  foil  is  lubricated  to  permit  easy  re- 
moval of  the  wax  model.  Wax  models  of  the  bases  are  best  made 
singly,  formed  with  a  thin  layer  of  wax  extending  down  on  the  sides  of 
the  saddle,  to  aid  later  in  contouring  its  surface  when  soldered,  as  shown 
at  E,  E  in  Fig.  916,  which  also  shows  the  sprue  wire  inserted. 


REMOVABLE  SADDLE  BRIDGE-WORK 


435 


The  post  or  pins  are  soldered  in  cast  or  swaged  bases  with  coin 
gold.  The  teeth  are  adjusted  in  the  bases  and  fitted  to  position  on  the 
saddle.  This  is  more  easily  done  with  cast  than  with  swaged  bases, 
as  they  fit  the  form  of  the  surface  of  the  saddle. 

When  the  teeth  and  bases  have  been  fitted  on  the  saddle,  th  teeth 
are  removed  from  the  bases  and  each  base  is  held  in  position  on  the 
saddle  with  wax  and  invested.  Fig.  917  shows  the  case  invested,  leaving 
the  lingual  surface  of  the  saddle  and  base  exposed.  The  inside  of  the 
base  into  which  the  crowns  fit  are  coated  with  rouge  or  antiflux  be- 
fore investment  to  prevent  invasion  of  the  solder  and  interference  with 
the  fit  of  the  porcelain.  In  the  operation  of  soldering,  the  bases  of  the 
crowns  are  first  united  to  the  saddle  by  flowing  under  them  20-carat 
gold  solder  from  one  side  to  the  other.  This  is- assisted  by  the  applica-  ' 
tion  of  the  large  flame  under  the  investment.  Sufficient  solder  is  then 
added  by  degrees  to  fill  in  depressions  between  the  bases  and  the  rounded 


Fig.  91 


Pig.  919. 


edge  of  the  saddle  so  as  to  even  its  surface  and  admit  of  proper  finish. 
To  accomplish  this  at  the  buccal  side,  it  is  frequently  necessary  to  again 
invest  the  bridge  and  apply  solder  at  that  part. 

The  teeth  are  then  cemented  with  oxyphosphate  in  their  bases  and 
the  edge  of  the  gold  burnished  closely  against  the  porcelain.  When  the 
cement  has  thoroughly  set,  all  parts  of  the  metal  are  finished.  Any 
interstices  that  may  exist  between  the  porcelain  and  the  gold  should  be 
filled  with  foil  or  Corona  gold  so  as  to  effect  continuity  of  structure. 
Fig.  918  illustrates  the  finished  removable  bridge.  Fig.  919  shows  the 
same  method  of  investing  the  gold  base  of  a  cuspid  detached-post  crown 
to  solder  it  to  the  floor  of  the  outer  cap  when  used  as  an  abutment. 

A  small  cast  saddle  may  be  made  to  include  in  one  casting  bases  for 
the  artificial  teeth  by  forming  them  on  the  wax  model  of  the  saddle. 

Saddles  could  be  advantageously  applied  to  the  typical  case,  Fig. 
892,  under  the  teeth  on  the  right  and  left  sides,  and  under  the  anterior 
teeth.     But  it  could  not  be  as  advantageously  done  in  the  latter  case. 


436  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

as  the  base  of  each  of  these  teeth  can  be  made  to  rest  and  slightly 
press  directly  against  the  tissues,  which  makes  an  agreeable  form  for 
the  patient.  Fig.  920  illustrates  the  case  with  saddles  under  the  side 
teeth. 

In  taking  an  impression  in  a  case  with  saddles  on  both  sides  of  the 
mouth,  pressure  must  be  applied  equally  to  both  saddles  at  the  time 


Fig.  920. 

the  impression  is  taken.  To  accomplish  this,  first  take  an  impression 
in  the  compound  with  the  saddles  and  crowns  in  position,  chill  and  re- 
move. Take  sadidles  and  crowns  from  the  impression  and  replace  them 
in  the  mouth.  Trim  the  compound  so  that  it  will  rest  only  against  the 
saddles  when  inserted,  as  shown  in  section  for  one  side  in  Fig.  921. 
The  impression  tray  is  then  filled  with  plaster  and  brought  to  position, 


Fig    921. 

with  the  exertion  of  sufficient  force  on  the  tray  to  cause  the  compound 
to  press  the  saddles  firmly  against  the  alveolar  ridge. 

Another  method  of  producing  pressure  on  a  saddle  when  taking  an 
impression,  is  to  place  small  wooden  posts  between  the  surfaces  of  the 
occluding  teeth  and  the  saddle,  of  sufficient  length  to  permit  the  introduc- 
tion of  the  tray.  The  patient  is  instructed  to  compress  the  tissues 
under  the  saddle  with  the  occluding  teeth  during  the  setting  of  the 


REMOVABLE  SADDLE  R RIDGE-WORK  437 

plaster.     An  impression  tray  with  slots  on  both  sides  that  will  ac- 
commodate the  posts  must  be  used.^ 

Construction  of  Porcelain-Faced  Solid  Gold  Dummies  for  Saddles. 
— Short  bicuspids  and  molars  of  this  form  may  be  constructed  as  follows: 
The  porcelain  facing  is  ground  to  position  on  the  saddle  and  a  plaster 
matrix  is  made  against  the  labial  aspect,  to  permit  the  facing  to  be 
removed  and  replaced  in  position.  A  wax  model  of  the  required  form 
of  the  remainder  of  the  dummy,  is  made  in  accordance  with  the  articu- 
lation, as  shown  in  section,  Fig.  922.  The  porcelain  facing  is  then 
removed,  carbon  points  inserted  in  the  pin  holes  and  a  cast  of  the  wax 
section  made  of  pure  or  slightly  alloyed  gold,  the  same  as  in  the  case  of 
a  "Cast  Box  Backing,"  as  described  on  pages  300  and  418.  The 
porcelain  facing  is  next  fitted  in  the  cast  section,  the  dummy  adjusted, 
the  gold  section  waxed  in  position  on  the  saddle,  and  the  porcelain 
facing  removed.  The  saddle  is  invested,  and  the  base  of  the  gold  sec- 
tion of  the  dummy  soldered  to  the  saddle  on  both  sides,  and  the  depres- 
sion between  it  and  the  rounded  edge  of  the  saddle  leveled  with  21- 


PiG.  922.  Fig.  923. 

carat  solder.  Fig.  923  shows  the  case  ready  to  receive  the  porcelain 
facings,  which  are  next  cemented  in  position.  Any  interstices  are  filled 
with  foil  or  Corona  gold  and  the  surface  of  the  gold  smoothed  and 
polished. 

Solid  Gold  Tooth  Dtmimies. — In  a  case  requiring  very  short  gold 
dummy  teeth  without  porcelain  facings,  a  wax  model  of  each  tooth  is 
made  and  cast.  The  gold  tooth  is  then  fitted  on  the  saddle  as  in  the 
previous  case,  invested  and  soldered  to  it,  on  buccal  and  lingual  sides. 

The  weight  of  all  forms  of  cast  solid  gold  dummies,  either  with  or 
without  porcelain  facings  may  be  lessened  by  the  removal  of  a  portion 
of  the  interior  of  the  wax  model  with  a  wax  absorber  (see  Figs.  457 
and  458). 

Vulcanite  Attachment. — In  saddle  and  plate  bridge-work  the  arti- 
ficial teeth — dummies — can  be  attached  to  the  saddle  or  plate  with 
vulcanite,  the  use  of  which  considerably  lessens  the  labor  of  construc- 
tion, and  for  upper  cases  has  the  advantage  of  lightness  as  compared 
with  gold.  Ordinary  porcelain  teeth  for  vulcanite,  or  Diatoric  teeth, 
are  mostly  used.     Two  or  three  loops  of  wire  or  a  narrow  strip  of  plate 

1  Dr.  Hart  J.  Goslee's  method. 


438  CROWN-,  BRIDGE  ,  AND  PORCELAIN-WORK 

should  be  soldered  on  the  saddle  as  an  attachment  (Fig.  924).  When 
a  strip  of  plate  or  a  small  wire  is  used,  it  is  best  attached  before  the  final 
swaging  of  the  saddle,  to  avoid  warping  that  might  occur  in  a  subsequent 
soldering.  Rouge  or  mica  placed  under  the  strip  or  wire  between  the 
points  to  be  soldered,  will  prevent  the  solder  from  uniting  the  strip  or 
wire  to  the  saddle  and  allow  it  to  be  raised  up  subsequently  when  the 
rubber  is  applied;  as  shown  in  Fig.  925. 

When  a  vulcanite  attachment  is  used,  the  work  should  be  so  con- 
ducted as  to  secure  not  only  an  attachment,  but  an  adhesion  of  the 
vulcanite  to  the  gold.  This  can  be  effected  by  cleaning  the  surface  of 
the  metal  that  comes  in  contact  with  the  rubber,  then  going  over  it 
lightly  with  a  small  scraper.  The  packing  of  the  rubber  should  be  done 
entirely  by  dry  heat;  water,  steam,  oil  or  grease  being  excluded  from 
direct  contact  with  the  surface  of  the  gold  or  rubber.  During  vulcani- 
zation the  flask  should  be  placed  on  a  stand  above  the  water  in  the 
vulcanizer.  When  so  conducted  the  result  will  amply  repay  for  any 
extra  labor  the  method  involves. 


Fig.  924.  Fig.  925. 

Extension  Saddle  Bridge 

This  form,  which  in  principle  is  a  cantilever,  is  employed  to  replace 
l^icuspids  and  molars  by  the  use  of  only  an  anterior  abutment.  The 
abutment  should  properly  consist  of  at  least  two  teeth  to  resist  the 
leverage  that  will  be  exerted  in  occlusion. 

Fig.  926  illustrates  a  removable  saddle  bridge  to  replace  two  lower 
molars.  The  abutment  consists  of  a  first  bicuspid  porcelain-faced  tube 
and  split-post  collar  crown,  united  to  a  second  bicuspid  all-gold  tele- 
scope, tube  and  split-post  crown. 

Fig.  927  shows  the  lingual  aspect  of  an  extension  bridge  retained  by 
a  split  bar  in  both  of  the  bicuspids,  and  the  method  by  which  the  bar 
to  the  first  bicuspid  is  attached  to  the  second  bicuspid  bar  by  a  flange 
extended  around  the  lingual  side  of  the  latter  resting  on  a  ridge.  Fig. 
928  shows  the  bridge  from  the  buccal  side  in  position. 

An  Adjustable  Saddle. — ^The  gradual  settling  of  the  saddle  and  the 
consequent  stress  exerted  on  the  abutment  in  occlusion  is  an  objection 
to  extension  bridge-work.  Injury  from  this  cause  may  be  remedied 
by  the  use  of  a  readjustable  saddle.  To  effect  such  a  form  of  construc- 
tion, the  artificial  extension  teeth  are  first  united  with  gold  to  the  abut- 


REMOVABLE  SADDLE  BRIDGE-WORK 


439 


ment  independent  of  the  saddle,  and  then  attached  to  the  saddle  with 
gutta-percha.  This  permits  the  saddle  to  be  easily  readjusted  to  the 
alveolar  ridge  without  changing  the  occlusion  of  the  teeth. 


Fig.  926. 


To  readjust  the  saddle,  heat  and  remove  it  and  slightly  increase 
the  quantity  of  gutta-percha.  The  bridge  and  saddle  are  then  heated 
sufficiently  to  soften  the  gutta-percha,  the  bridge  is  adjusted  to  posi- 
tion in  the  mouth  by  first  using  pressure  with  the  fingers  and  next  by  the 


Pig.  927. 

patient  occluding  the  teeth.  Remove  and  reheat  bridge  and  gutta- 
percha and  readjust  until  the  bridge  assumes  its  proper  position. 
Fig.  929  outlines  in  section  the  plan  of  the  formation  of  a  porcelain 


tooth  with  a  gold  base  for  such  a  bridge  and  the  pin  that  secures  it  to 
the  saddle.  Fig.  930  is  another  form  consisting  of  a  hollow  gold  tooth 
with  a  loop  of  wire  instead  of  a  pin.  This  latter  form  is  the  best  to 
use  when  short  teeth  are  required. 


440 


CROWN-,  BRIDGE-,  AND  PORCELAIN  WORK 


Vulcanite  Extension  Saddle. — Fig.  931  outlines  a  bridge  of  this 
style.  The  dummy  teeth  are  formed  of  hollow  reinforced  gold  crowns. 
The  gold  dummies  are  placed  in  occlusion,  leaving  a  space  of  about 
one-eighth  inch  between  the  cervices  and  the  alveolar  ridge,  and  in 
this  position  are  securely  soldered  to  each  other  and  to  the  abutment. 
An  impression  is  next  taken  of  the  alveolar  ridge  in  correct  relationship 


Fig.  929. 


Pig.  930. 


to  the  bridge  with  impression  compound.  This  is  done  by  placing  a 
suitable  quantity  of  the  compound  over  the  necks  and  in  the  hollows 
of  the  gold  dummies,  then  adjusting  and  pressing  the  bridge  to  position 
in  the  mouth.  The  bridge  is  removed,  a  plaster  model  made,  and  a 
vulcanite  saddle  formed.  The  base  of  such  a  saddle  can  be  renewed 
at  any  time  in  exact  conformation  with  the  alveolar  ridge,  by  removing 


Fig.  931. 

the  bridge  and  slightly  indenting  the  surface  of  the  vulcanite  over  the 
alveolar  ridge,  placing  impression  compound  or  wax  upon  it,  taking  an 
impression  of  the  ridge,  and  substituting  vulcanite  for  the  compound 
or  wax.  This  is  a  form  of  saddle  very  suitable  to  apply  when  teeth  have 
been  recently  extracted  and  absorption  of  the  alveolar  process  is  still 
taking  place. 


CHAPTER  V 

REMOVABLE  PLATE  BRIDGE-WORK 

MERITS— LIMITATIONS — CLASPS  WITH  LUGS — ^PREPARATION  FOR  CLASP 
ATTACHMENT — SHAPING  CLASPS — COLLAR  METHOD — CAST  CLASPS — 
CLASPS  AND  LUGS — FORMATION  OF  INLAY  LUGS — LUGS  FOR 
NATURAL  CROWNS — CONSTRUCTION  OF  A  PLATE  BRIDGE — UNITING 
ATTACHMENTS  TO  PLATE — TO  CORRECT  WARPING — A  FREQUENT 
CAUSE    OF    WARPING. 

Removable  Plate  Bridge-work  is  practically  plate-work  sustained 
by  clasps  or  collars  with  anchorage  lugs,  or  some  form  of  attachment  that 
fastens  or  anchors  on  the  abutment  teeth,  crowns  or  inlays.  The  in- 
sertion of  dentures  of  this  form  of  construction  and  which  of  late  is 
growing  in  favor,  is  not  of  recent  conception,  having  been  described  in 
this  treatise  in  1888  and  by  Dr.  W.  G.  A.  Bonwill  in  1893. 


Fig.  932. 

Fig.  932  shows  a  plate  bridge  to  replace  two  superior  bicuspids  sup- 
ported by  clasps  on  the  cuspid  and  molar  with  lugs  resting  on  shoulders 
at  the  points  A  A,  Fig.  933.  In  this  case  the  clasps  after  having  been 
shaped  and  soldered  to  the  plate  were  heated  and  their  inner  surface 
veneered  with  wax.  When  the  veneer  had  cooled,  a  layer  of  soft  wax 
was  placed  over  the  approximal  and  lingual  surfaces  of  the  veneer  and 
the  plate  and  clasps  pressed  to  position  in  the  mouth  and  removed. 
Platinum  foil  >^ooo  to  3-f  000  was  annealed  and  evenly  placed  over  that 
part  of  the  surface  of  the  wax  that  had  covered  the  approximal  and 
lingual  surfaces  and  also  the  edge  of  the  occlusal  surface  of  the  molar. 

441 


442 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


The  plate  was  inserted,  pressed  firmly  against  the  tissues  and  the  edge 
of  the  wax  pressed  with  the  finger  against  the  foil.  The  plate  was 
removed,  invested  and  solder  flowed  between  the  clasps  and  foil. 
Surplus  foil  and  gold  were  removed,  leaving  only  enough  at  the  edges 


Fig.  933. 

of  the  clasps  on  the  edge  of  the  occlusal  surface  of  the  molar  and  lingual 
surface  of  the  cuspid  for  support. 

Fig.  934  shows  a  plate  bridge  to  replace  a  left  superior  lateral. 
Figs.  935,  936  and  937  illustrate  and  explain  the  form  of  the  construc- 
tion.^ 

Figs.  938  and  939  show  Dr.  Bonwill's  method  of  replacing  a  bicuspid 
and  a  molar. ^ 


Fig.  934- 

Merits. — In  artificial  restorative  methods  by  removable  plate  bridge- 
work,  mutilation  of  the  supporting  teeth  or  removal  of  pulps  is  seldom 
necessitated.  For  these  reasons  replacement  of  absent  teeth  may  often 
be  effected,  which  would  not  be  considered  advisable  by  other  methods 
or  be  sanctioned  by  the  patient. 

^  The  cases  shown  in  Figs.  932  to  937  were  described  in  the  first  edition  of  this 
treatise  in  1888. 

2  Cases  described  by  Dr.  W.  G.  A.  Bonwill  in  the  International  Dental  Journal  in 
1893. 


REMOVABLE  PLATE  BRIDGE-WORK 


443 


Pig.  935. — Shows  in  section,  central  incisor  root  with  tube  and  split  post  in  canal. 

A  B 


Fig.  936. — A,  Cap  and  tube  for  central;  B,  half-collar  central  crown  with  split  post; 

C,  clasp  for  cuspid. 


Fig.  937. — Shows  cuspid  with  gold  filling.     A,  Notch  for  lug. 

A 


Pig.  938. 


Fig.  939. 


444  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Limitations. — The  use  of  removable  bridge  plates  is  best  confined  to 
cases  of  replacement  of  posterior  teeth  where  the  alveolar  ridge  is  ab- 
sorbed: also  where  the  character  of  the  abutment  teeth  for  stability, 
health  or  other  conditions  suggests  the  method.  It  is  a  method  seldom 
used  for  incisors  or  cuspids  except  when  such  teeth  can  be  placed  on 
the  same  plate  that  is  being  used  to  replace  posterior  ones. 

Clasps  with  Lugs. — In  removable  plate  bridge-work,  clasps  with 
lugs  are  used  on  either  natural  or  artificial  crowns.  In  natural  teeth 
the  lug  is  usually  set  in  an  inlay  or  filling,  and  in  artificial  crowns  in  a 
socket  made  in  the  crown.  A  lug  aids  in  retaining  a  clasp  in  position 
to  better  resist  lateral  strain,  enables  it  to  bear  pressure  exerted  on  the 
denture  in  occlusion,  prevents  impingement  on  the  gingival  margin, 
and  when  applied  to  a  natural  crown  lessens  liability  to  abrasion  of  the 
enamel  by  steadying  the  clasp.  The  use  of  this  form  of  clasp  is  increas- 
ing in  favor,  as  its  application  often  avoids  the  alternative  of  a  capping 
or  crowning  operation. 

The  clasps  are  made  of  iridio-platinum  gold  or  clasp  gold.  The 
portion  of  the  clasp  requiring  resiliency  should  be  left  entirely  free  and 
not  reinforced  with  solder.  In  the  formation  and  use  of  clasps,  the 
following  points  are  to  be  considered: 

1.  Flat  plate  clasps  are  most  suitable  when  the  natural  crowns  are 
nearly  straight-sided  and  for  clasping  similarly  shaped  artificial  crowns. 
Half-round  wire  clasps  are  best  applied  to  natural  crowns  with  contour 
and  to  short  crowns. 

2.  A  clasp  that  encircles  four  angles  of  a  crown,  obtains  a  better 
hold  than  if  it  encircles  only  three,  and  a  clasp  to  reliably  grasp  must 
encircle  at  least  three  angles.  When  less  in  length  a  clasp  will  only 
press  against  the  tooth  or  crown  unless  it  is  retained  in  position  by  a 
lug. 

3.  For  strength  the  widest  or  heaviest  part  of  the  clasp  should  be 
nearest  its  union  with  the  denture. 

4.  The  strength  and  rigidity  of  a  clasp  lessens  as  it  extends  from 
where  it  is  united  with  the  denture.  Consequently  a  clasp  should  be 
uniform  in  width  and  thickness,  and  if  it  tapers,  should  do  so  only 
slightly  towards  the  ends  or  points. 

5.  A  clasp  should  extend  over  the  surface  of  the  sides  of  a  natural 
or  artificial  crown,  not  nearer  than  one-sixteenth  to  one-eighth 
of  an  inch  from  the  gingival  margin,  to  avoid  irritation  of 
that  membrane.     The  edge  of  a  clasp  must  entirely  clear  the  occlusion. 

Preparation  for  Clasp  Attachment. — Clasps  should  be  placed  and 
shaped  to  move  on  and  off  as  nearly  as  possible  parallel  with  each  other 
and  any  other  attachments  present.     The  adaptation  of  a  clasp  as 


REMOVABLE  PLATE  BRIDGE-WORK 


445 


close  as  is  practical  to  the  contour  of  a  natural  tooth  when  adjusted 
is  all  that  is  expected  or  required.  Adjustment  and  adaptation  to 
some  teeth  is  much  facilitated  by  slightly  trimming  and  then  polishing 
one  or  more  projecting  points  of  the  enamel.  This  is  especially  the 
case  when  teeth  tip  out  of  line.  A  plaster  study-model  of  the  case  will 
guide  this  part  of  the  work.  In  the  case  of  artificial  crowns,  fiat  plate 
clasps  should  be  used,  shaped  as  straight  and  close  as  possible  to  the 
sides. 

As  a  pattern  for  a  plate  clasp,  shape  on  the  model  or  die  of  the  tooth 
a  piece  of  thin  annealed  sheet  copper  or  tin  a  shade  wider  and  longer 
than  required.  Use  gold  clasp  plate  not  less  than  gage  No.  24  and 
half-round  wire,  gages  Nos.  12,  13,  or  14;  the  larger  the  tooth,  the 
greater  the  thickness  of  wire,  so  as  to  proportionately  insure  strength 
and  permit  any  necessary  trimming.  The  labial  section  of  a  plate 
clasp  on  an  inferior  cuspid  ought  to  be  made  wide,  and  on  a  superior 
cuspid  as  wide  as  it  properly  can  be,  without  causing  too  much  exposure 
of  the  metal. 


Fig.  941 


Fig.  942. 


Fig.  943. 


Shaping  Clasps.— A  clasp  after  being  bent  with  suitable  pliers  is 
most  easily  shaped  to  the  form  of  a  natural  crown  by  the  aid  of  a  die. 
The  best  method  is  to  take  a  sectional  impression  of  the  tooth  and  make 
an  amalgam  die.  From  the  amalgam  die  take  an  impression  in  a  tube 
with  moldine  and  run  a  fusible  metal  die.  Use  the  fusible  die  for  the 
preliminary  shaping  and  the  amalgam  for  the  final.  In  the  case  of  a 
gold  crown,  fill  the  interior  with  fusible  metal,  and  use  the  crown  as  a 
die.  In  the  shaping  and  trimming  of  clasps,  frequent  transferring 
from  the  die  to  the  model  and  annealing  are  necessary.  In  the  construc- 
tion of  the  half-round  wire  clasp,  it  should  be  brought  just  over  the  curve 
of  contour  of  the  tooth  so  that  it  springs  to  position. 

Collar  Method.— To  accurately  shape  clasp  gold  plate  to  the  curved 
form  of  many  crowns  is  very  difficult,  owing  to  the  rigidity  and  resili- 
ence of  the  alloy.  The  following  method  has  lately  been  practiced  by 
the  author:  Shape  around  the  die  of  the  tooth  or  crown,  a  wide  band  of 
thin  copper  and  lap  and  solder  the  ends  together,  thus  forming  a  collar, 
Fig.  940.  Trim  and  shape  the  cervical  and  occlusal  edges  of  this  band 
to  the  form  and  width  desired  for  the  clasp,  as  shown  in  the  case  of  a 


446 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


cuspid  in  Fig.  941,  usually  a  difficult  tooth  to  clasp.  Cut  the  band 
midway  between  the  intended  separation  of  the  ends. of  the  clasp,  as 
marked  in  this  case  at  S,  Fig.  940.  Open  out  the  band  and  use  it  as  a 
pattern  to  cut  the  clasp  gold  (Fig.  942).  Anneal  the  gold  clasp,-  bend 
it  in  a  circle  and  solder  the  ends  together  with  a  very  small  piece  of 
solder.  Slip  the  gold  clasp  band  over  the  die  of  the  tooth  and  by  fre- 
quent bending,  tapping  with  a  riveting  hammer  and  annealing,  it  can 
be  accurately  shaped.  When  shaped,  cut  the  gold  collar  where  the  ends 
were  joined,  and  trim  the  ends  to  the  desired  length,  making  it  a  clasp 
(Fig.  943)- 

Cast  Clasps. — Cast  clasps  are  used  to  some  extent  in  preference  to 
shaping  plate  or  wire  to  the  form  of  the  tooth.  A  cast  clasp  will  fit 
the  contour  of  the  crown  more  accurately  but  will  lack  the  strength 
and  resiliency  of  rolled  or  drawn  metal.  The  lack  of  resiliency  and  the 
close  fit  of  a  cast  clasp  will  not  permit  it  to  be  adjusted  on  a  crown  with 


Fig.  944. 


Fig.  945. 


sharp  points  of  contour.  Its  use  must  therefore  be  confined  to  artifi- 
cial crowns,  or  to  natural  crowns  whose  contour  is  or  can  be  made 
favorable  to  its  application.  Molars  and  bicuspids  require  httle  or  no 
reduction  of  contour,  while  the  form  of  cuspids  usually  necessitates 
considerable  shaping.  The  cuspid  illustrated  at  A  in  Fig.  944  will  be 
used  as  a  typical  case.  The  distal  side  requires  to  be  shaped  to  the 
form  shown  at  B,  and  the  surface  of  the  enamel  polished.  A  sectional 
impression  is  taken  with  impression  compound,  and  a  model  made  of 
inlay  investing  material.  On  this  model  a  wax  pattern  of  the  clasp  is 
formed,  Fig.  945.  This  is  best  done  by  first  veneering  the  surface  of 
the  model  with  melted  wax,  using  a  hot  spatula,  then  shaping  inlay  wax 
over  the  veneer  to  the  required  form  for  the  clasp  and  lug.  A  sprue  wire 
is  inserted  in  the  heaviest  part  of  the  wax,  and  both  wax  pattern  and  the 
model  invested  in  a  casting  flask  and  the  clasp  cast.  The  lug  is  cast 
with  the  clasp  as  a  part  of  it.  In  the  case  of  a  cuspid  or  incisor,  a 
small  portion  of  the  gold  placed  over  the  surface  of  the  contour  on  the 
lingual  side  will  act   as  a  lug.     Fig.  946  illustrates  an  inferior  right 


REMOVABLE  PLATE  BRIDGE-WORK 


AAl 


second  molar  with  a  wax  model  of  a  clasp,  and  a  sprue  inserted  ready  to 
invest. 

Another  method  of  cast  clasp  construction  is;  make  an  amalgam  die 
of  the  prepared  tooth,  lubricate  the  surface  and  wipe  off  all  surplus. 
Form  on  the  die  a  wax  model  of  the  required  clasp  and  lug,  insert  sprue, 
cover  the  surface  of  the  wax  with  a  thick  coating  of  the  investing  ma- 
terial and  when  it  has  thoroughly  set,  remove,  invest  and  cast.  The 
wax  clasp  model  is  best  formed  by  first  adapting  a  layer  of  stiff  wax 
to  the  surface  of  the  die  and  finishing  with  a  softer  grade. 


Clasps  and  Lugs. — Cuspids  are  not  so  well  suited  for  clasp  and  lug 
attachments  as  bicuspids  and  molars.  When  a  lug  is  applied  to  a  cuspid 
with  a  vital  pulp,  the  gold  to  support  the  lug  can  usually  be  more 
reliably  supported  by  a  filling  with  undercuts,  than  in  the  form  of  a 
cemented  inlay  (Fig.  947).  If  the  tooth  is  pulpless,  a  lug  with  a  lock 
pin  is  the  preferable  form  to  apply  with  the  clasp  (Fig.  948). 


Pig.  947. 


Fig.  948. 


Fig.  949. 


An  occlusal  lug  without  the  use  of  an  inlay  may  be  applied  to  a  clasp 
to  rest  on  the  enamel  of  a  tooth  when  no  occluding  tooth  is  present,  as 
shown  in  Fig.  949.  A  piece  of  as  heavy  half-round  clasp  wire  as  the 
case  will  permit  is  best  used  to  form  the  lug.  The  sides  and  end  of  the 
lug  should  be  closely  fitted  and  tapered  off  to  the  surface  of  the  tooth. 

Formation  of  Inlay  Lugs. — Inlay  lugs  are  usually  made  by  casting 
or  by  the  use  of  a  matrix.  A  wax  model  or  matrix  of  the  form  of  the 
lug  is  made  in  accordance  with  the  occlusion.  Applied  to  a  flat  clasp 
the  lug  is  made  to  fit  against  the  inner  side  of  the  clasp  (Fig.  950). 


44S 


CROWN-,  BRIDGE-.  AXD  PORCELAIN -WORK 


For  a  half-round  wire  clasp,  the  lug  is  formed  to  extend  over  the  wire 
clasp  so  that  the  lug  can  be  securely  united,  as  shown  in  Fig.  951. 

A  cast  lug  is  cast  separately,  then  soldered  to  the  clasp.  In  the 
use  of  a  matrLx  lug,  the  matrix  is  formed,  the  clasp  adjusted,  the  matrix 
filled  with  wax  and  attached  to  the  clasp.  Clasp  and  matrix  are  re- 
moved, invested,  and  the  matrix  filled  and  attached  to  the  clasp  with 
hard  solder,  and  the  lug  is  trimmed  to  shape.  A  small  lug  to  rest  in 
a  correspondingly  small  slot  in  a  gold  tilling  should  be  made  by  the  matrix 
method,  using  3^2000  platinum  foil  for  the  matrix. 

Lugs  for  Natural  Crowns. — Lugs  to  clasps  that  only  rest  on  the  teeth 
clasped  are  to  be  extended  but  a  short  distance  on  their  surface  (Fig. 


Fig.  950. 


Pig.  951. 


Fig.  952. 


Fig.  953. 


Pig.  954. 


Pig.  955. 


949').  The  slot  for  the  lug  in  an  inlay  or  filling  should  be  given  a  slight 
retentive  oval  form,  as  sho-mi  in  Fig.  952.  A  lug  in  a  gold  cap  crown 
is  inserted  in  a  slot  or  box  (Fig.  953).  It  is  made  by  removing  the  re- 
quired portion  of  the  occlusal  surface  and  approximal  side  of  the  crown 
before  the  cusps  are  reinforced,  then  inserting  the  box  and  soldering  it 
in  position  from  the  inside,  and  at  the  same  time  reinforcing  the  cusps. 
(Fig.  607,  Part  IV,  Chapter  III). 

Another  method,  when  a  cast  gold  occlusal  cusp-cap  is  used,  is  to 
solder  a  gold  floor  to  the  occlusal  edge  of  the  collar,  and  cast  an  occlusal 
cusp-cap  with  a  slot  (Fig.  954).  and  solder  the  cusp-cap  to  the  floor. 

In  case  of  a  porcelain-faced  gold  bicuspid  crown,  the  slot  for  the 
lug  is  made  as  follows:  A  vertical  hole  is  first  drilled  in  the  finished 


REMOVABLE  PLATE  BRIDGE-WORK 


449 


crown  to  within  a  short  distance  of  the  floor  of  the  root-cap,  when  two 
cuts  are  made  with  a  fine  saw  on  the  side,  the  gold  gradually  removed, 
and  the  cavity  shaped  with  small  stones  and  burs.  If  exposure  of  the 
clasp  on  the  buccal  side  is  objectionable,  form  a  narrower  and  deeper 


^ 


Fig.  956. 


FxG.  957. 


slot,  of  retentive  form,  from  the  occlusal  surface  toward  the  floor,  and 
extend  the  clasp  only  on  the  approximal  and  lingual  sides.  So  placed, 
it  will  furnish  a  fairly  reliable  attachment  (see  Fig.  955,  viewed  from 


fe  0j]  %  ^ 


D 


Pig.  958. 


Fig.  959. 


the  occlusal  surface).  The  use  of  such  a  lug  and  clasp  on  a  natural 
crown  is  not  practicable,  unless  the  tooth  is  pulpless,  so  as  to  admit  of 
the  insertion  of  a  securely  anchored  inlay  and  a  small  pin  in  the  lug. 

BCD  E  F 


Fig.  960. 

Fig.  956  illustrates  a  gold  crown  with  an  oval-shaped  lug  rest  cavity, 
and  a  cast  lug  united  to  a  flat  gold  clasp. 

Fig.  957  shows  a  gold  porcelain-faced  bicuspid  crown,  in  which  is 
cut  a  narrow  deep  cavity  for  the  lug;  to  further  elucidate  the  method 

29 


4  50  CROWN-,  BRIDGE-  AND  PORCELAIN-WORK 

two  friction  lugs  are  also  shown,  one  united  to  a  flat,  and  the  other  to 
a  half-round  clasp. 

Fig.  958  is  a  bicuspid,  A,  with  a  cast  inlay,  B,  wire  clasp  with  lock- 
pin  lug,  C,  and  a  die  in  which  the  inlay  was  made  and  the  matrix  for 
the  lug  swaged,  D. 

Fig.  959  is  an  inlay  in  a  molar.  A,  plain  matrix,  B,  pin  matrix,  C, 
and  parts  assembled  to  form  the  lock-pin  lug,  D. 

Fig.  960  illustrates  the  construction  of  a  lock  pin  in  a  central  used 
as  a  supporting  attachment ;  A  and  B  show  the  cavity  prepared  for  the 
cast  inlay  with  pin;  C,  compound  impression  with  a  steel  pin  embedded; 
D,  same  in  flask  ready  to  pack  an  amalgam  die;  E,  die  completed;  F, 
matrix  for  lug  and  same  adjusted  in  inlay. 

Construction  of  a  Plate  Bridge 

The  plate  used  is  made  either  by  swaging  or  casting,  preferably  by 
swaging  for  large  plates  and  by  casting  for  small  ones.  The  swaged 
plate  is  formed  of  18-  to  20-carat  gold,  gage  No.  26,  reinforced  across 
the  connecting  sections.  The  plate  is  cut  a  trifle  larger  in  size  than  is  re- 
quired. The  cross  sections  are  reinforced  by  the  addition  of  successive 
narrow  layers  of  plate  about  gage  32  to  34  swaged  one  at  a  time,  and 
united  with  the  least  possible  quantity  of  solder.  The  swaged  plate 
is  fitted  in  the  mouth,  and  to  the  abutment  attachments. 

Uniting  Attachments  to  Plate. — A  small  plate  with  two  attachments 
may  often  be  cemented  with  wax  to  them  separately  or  together, 
pressure  exerted  on  the  plate,  the  wax  chilled,  plate  and  attachment 
or  attachments  removed,  invested  and  united  with  solder.  In  this 
method  it  is  preferable  to  first  unite  the  most  difiicult  attachment  to 
remove. 

The  method  generally  practiced  is  to  place  each  attachment  in 
position,  exert  pressure  on  the  plate.,  take  a  plaster  impression  and 
remove  plate  and  attachments  in  position.  Fill  impression  with 
investing  material,  remove  plaster  impression,  add  more  investing 
material  and  solder  attachments  to  plate.  A  Roach  sectional  impres- 
sion tray  is  useful  in  this  part  of  the  work,  as  pressure  can  be  exerted  on 
the  plate  by  the  flange  of  the  tray  in  taking  the  impression. 

When  clasp  lug  attachments  are  the  form  to  be  used,  plate  bridges 
can  be  constructed  by  forming  the  plate  first,  taking  a  plaster  impres- 
sion with  pressure  on  the  plate,  filling  the  impression  of  the  teeth  with 
amalgam  and  the  remainder  of  the  impression  with  plaster.  Clasps  with 
lugs  are  then  made  on  the  amalgam  models  of  the  abutment  teeth, 
plate  and  clasps  cemented  together,  removed  and  united  to  the  plate. 


REMOVABLE  PLATE  BRIDGE-WORK 


451 


Pig.  961. 


Fig.  962. 


Fig.  963. 


452 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Before  investing  attachments  and  plate  see  that  the  attachments 
touch  or  nearly  touch  the  plate;  if  they  do  not,  add  an  extension  by 
separately  investing  and  soldering. 

The  plate  and  attachments  are  adjusted  in  the  mouth,  any  inter- 
ference with  the  occlusion  corrected,  and  a  "bite"  taken  with  plaster 
or  compound.     The  case   is  then  finished,   using  porcelain  teeth  at- 


PlG.  964. 


tached  either  with  gold  or  vulcanite,  as  in  saddle  bridge-work.  When 
the  plate  extends  on  both  sides  of  the  mouth,  vulcanite  is  preferably 
used  for  lightness  and  to  avoid  risk  of  warping. 

Figs.  961  and  962  show  the  restoration  of  a  lower  molar  with  half- 
round  wire  and  lug  attachments. 

Figs.  963  and  964  show  a  removable  extension  plate  bridge.  It 
consists  of  a  gold  crown  with  porcelain  facing  on  the  right  cuspid,  all- 


REMOVABLE  PLATE  BRIDGE-WORK 


453 


gold  crowns  on  the  adjoining  bicuspids,  and  a  gold  crown  on  the  left 
bicuspid.  The  denture  is  made  of  a  swaged  plate  with  reinforced 
palatal  bar  and  vulcanite  attachment  for  the  porcelain  teeth.  The  lugs 
are  oval-shaped  and  are  connected  by  bars. ' 

The  case  illustrated  in  Fig.  965  shows  a  method  of  constructing  a 
partial  lower  denture  in  which  the  stress  on  the  retaining  teeth  is  re- 
lieved by  the  use  of  elliptical  springs  to  join  the  clasps  and  the  plate. 


Fig.  965. 

The  practical  value  of  such  a  method  is  as  yet  problematical.  The 
right  and  left  sections  of  lower  dentures  can  be  connected  by  a  narrow 
reinforced  strip  of  plate  or  a  bar.  Made  in  either  form,  a  slight  space 
should  be  left  between  the  strip  or  bar  and  the  surface  of  the  model,  so 
that  no  pressure  shall  be  brought  to  bear  upon  the  tissue  under  it.  This 
is  definitely  and  uniformly  accomplished  by  placing  on  this  part  of  the 
plaster  model  successive  layers  of  pattern  tin  to  form  a  thickness  of 


Pig.  966. 

about  gage  No.  22  to  24  before  making  the  mold  for  casting  the  die 
(Fig.  966).  When  a  connecting  strip  of  the  plate  is  used  instead  of  a 
bar  in  a  lower  case,  such  as  is  described,  it  should  be  reinforced  by  at 
least  three  additional  strips  of  clasp  gold,  gages  Nos.  32  to  34,  each 
strip  being  cut  a  little  narrower  than  the  preceding  one  as  they  are 
swaged  (Fig.  967).  Each  strip  should  first  be  caught  at  the  ends  with 
1  Case  of  Dr.  R.  F.  Getz. 


454 


CROWN',  BRIDGE-,  AND  PORCELAIN-WORK 


an  atom  of  hard  solder  to  retain  it  in  position  when  swaged.  Only 
enough  solder  to  barely  unite  the  several  strips  should  be  used.  The 
united  strips  are  then  trimmed  to  the  required  width,  the  edges  rounded 


Pig.  967. 


Fig.  968. 


Fig.  969. 


Fig.  970. 


and  the  whole  polished  and  given  a  final  swage.  A  very  rigid  slightly 
oval-shaped  connecting  link  is  thus  formed  and  one  that  will  offer  the 
least  possible. obstruction  to  the  tongue,  as  shown  in  Fig.  968. 


REMOVABLE  PLATE  BRIDGE-WORK  455 

Figs,  969  and  970  show  a  lower  removable  plate  bridge  with  clasp 
and  lug  attachments  that  was  made  to  replace  a  cemented  bridge. 
The  method  of  the  construction  of  the  cemented  bridge  kept  the  mouth 
in  a  septic  condition,  as  it  could  not  be  properly  cleaned  by  the  patient, 
by  whom  the  denture  with  which  it  was  replaced  has  been  satisfactorily 
worn  for  several  years.  Pressure  of  the  narrow  reinforced  strip  con- 
necting the  right  and  left  sides  of  the  plate  was  obtained  as  described 
in  the  preceding  case."^ 

To  Correct  Warping. — In  removable  plate  bridge-work,  if  warping 
occurs  in  the  soldering  of  attachments  on  opposite  sides  of  the  mouth, 
it  should  be  corrected  before  the  artificial  teeth  are  attached.  This  was 
done  in  the  case  illustrated  in  Fig.  969,  as  follows:  An  impression  of  the 


Fig.  971. 

surface  of  the  zinc  die  on  which  the  plate  was  swaged  was  taken  in 
plaster.  On  its  removal  from  the  die,  the  plaster  around  the  locality 
of  the  clasps  and  attachments  was  trimmed  so  that  the  plaster  mold 
would  rest  on  the  surface  of  the  plate  without  touching  them,  as  shown 
in  Fig.  971.  This  impression  mold  was  then  cast  in  lead  and  used  as 
a  die  to  swage  the  plate  against  the  zinc  die  and  remedy  the  warping. 
Should  any  part  of  a  die  under  the  attachments  interfere  with  the  ad- 
justment of  the  plate  on  the  die,  remove  the  metal  of  the  die  at  those 
points  with  a  file  or  coarse  carborundum  wheel. 

A  frequent  cause  of  warping  is  immersion  in  water  of  an  invested 
gold  plate  immediately  after  a  soldering  operation  to  gain  time.  The 
water  absorbed  is  instantly  converted  into  steam.  The  steam  by  press- 
ing against  the  surface  of  the  plate  tends  to  distort  it. 

'  Case  of  the  author's. 


CHAPTER  VI 

GENERAL  APPLICATION  OF  REMOVABLE  BRIDGE-WORK 

CENTRALS,     LATERALS     AND     CUSPIDS — ^BICUSPIDS    AND    MOLARS — CON- 
NECTING BARS  TO   SADDLES — CAST  SADDLES  AND  PLATES 

The  form  and  construction  of  removable  bridge-work  is  further 
explained  in  its  application  to  the  following  typical  cases. 

Centrals,  Laterals  and  Cuspids. — Fig.  972  shows  one  of  the  methods 
of  constructing  a  removable  central.  The  pulp  is  removed  from  the 
adjoining  central  and  an  inlay  tube  and  split  post  inserted  to  support 
the  dummy  central.     A  lug  resting  on  the  lateral  is  used  to  assist  the 


Fig.  972. 


Fig.  973. 


abutment    in  resisting  pressure  in  occlusion  on  the  dummy  central. 
Fig.  973  shows  the  bridge  in  position. 

Fig.  974  shows  another  method  in  which  a  removable  half-collar 
crown  with  a  tube  and  split  post  is  used  for  an  abutment.  The  re- 
mainder of  the  construction  is  the  same  as  in  the  preceding  method. 
A  filling  or  inlay  for  the  lug  to  rest  on  is  not  always  indicated.  If 
injury  results  from  the  presence  of  the  lug,  a  filling  or  inlay  can  at  any 
time  be  easily  inserted,  as  the  denture  is  removable. 

In  cases  of  short  teeth  or  forcible  and  direct  occlusion,  the  restoration 
of  a  single  central  may  demand  the  lateral  in  addition  to  the  central 
as  a  retaining  abutment,  as  shown  in  Fig.  975,  in  which  inlays  with  tube 
and  split-post  attachments  are  used. 

456 


GENERAL  APPLICATION  OF  REMOVABLE  BRIDGE-WORK      457 


The  restoration  of  a  lateral  is  best  effected  by  using  the  cuspid  as  a 
retaining  abutment,  as  shown  in  Fig.  976. 

The  restoration  of  two  centrals  generally  requires  the  support  of 
the  cuspids  as  retaining  abutments.  Bars  are  extended  from  the  cus- 
pids to  the  artificial  centrals  over  the  lingual  side  of  the  laterals,  resting 
either  on  the  surface  or  in  a  groove  in  an  inlay. 


Fig.  974. 


Fig.  975- 


A  cuspid  dummy,  to  resist  the  force  of  occlusion,  requires  two  re- 
taining abutments,  the  bicuspid  and  lateral. 

Bicuspids  and  Molars. — A  first  bicuspid  is  best  replaced  by  a 
retaining  abutment  on  the  second  bicuspid  and  a  lug  on  the  cuspid,  as 
shown  in  Fig.  977,  and  in  position  in  Fig.  978.     A   second  bicuspid 


Pig.  976. 


Pig.  977. 


demands  a  retentive  abutment  on  the  first  molar  and  a  supporting 
abutment  additionally  on  the  first  bicuspid. 

Fig.  979  shows  a  bridge  of  the  superior  right  first  and  second  bi- 
cuspids supported  by  a  tube  and  split-post  crown  on  the  cuspid  and  a 
split  bar  in  the  molar  gold  crown. 

The  replacement  of  a  lower  second  bicuspid  and  a  molar  with  a 


458 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


saddle  bridge  is  shown  in  Fig.  980.  A  porcelain-faced  gold  crown  with 
a  split  post  was  placed  on  the  first  bicuspid  as  the  anterior  abutment. 
As  the  second  molar,  forming  the  posterior  abutment,  tipped  forward, 
a  gold  crown  with  a  split  bar  was  preferably  used. 


Pig.  978 

Fig.  981  shows  the  typical  case  already  described  (Fig.  892),  re- 
tained with  tube  and  split-post  crowns  on  the  cuspids,  a  split  bar  in  an 
inlay  in  the  left  molar  and  a  split  bar  in  an  all-gold  crown  on  the  right 
molar. 


Fig.  979. 

Fig.  982  shows  a  case  replacing  the  right  superior  first  and  second 
molars  and  the  left  second  bicuspid  and  first  molar,  by  the  split-bar 
method  and  saddles.     On  the  right  side  the  extension  saddle  is  con- 


PlG.  980. 


nected  by  a  bar  to  the  saddle  on  the  left  side  to  counteract  leverage 
and  for  additional  support.     Fig.  983  shows  the  denture  in  position. 
To  obtain  alveolar  support  for  the  saddle  a  small  space  can  be  left 


GENERAL  APPLICATION  OF  REMOVABLE  BRIDGE-WORK      459 


Fig.  982. 


460 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


under  each  of  the  spht  bars  in  the  boxes.  This  space  is  evenly  propor- 
tioned by  placing  in  the  bottom  of  each  box,  a  piece  of  pure  gold,  gage 
22,  when  the  bars  are  adjusted  to  the  saddles,  and  removing  the  pieces 
of  gold  after  the  bars  are  united  to  the  saddles.  In  this  manner  saddles 
are  permitted  to  settle  uniformly.  In  the  case  of  an  extension  saddle 
it  prevents  the  saddle  from  settling  at  only  the  posterior  end  and 
thereby  straining  the  abutments. 

This  method  of  constructing  superior  dentures  of  right  and  left 
saddles  connected  by  a  bar  is  not  regarded  with  favor  by  the  author, 
who  considers  a  gold  plate  covering  a  portion  of  the  palate  supported 
by  clasps  with  lugs  preferable.  The  latter  form  of  denture  lessens  the 
stress  on  the  abutment  teeth  or  crowns  and  is  not  so  complicated  in 
construction.     If  the  anterior  portion  of  such  a  plate  is  removed,  so  as 


Fig.  983. 


to  leave  a  space  between  the  edge  and  the  anterior  teeth  of  at  least 
one-eighth  inch,  and  the  posterior  edge  is  extended  back  a  moderate 
distance,  the  additional  portion  of  the  palate  covered  compared  to 
that  covered  by  a  bar  will  not  make  a  very  material  difference  to  the 
patient.  What  is  here  stated  respecting  superior  right  and  left  saddles 
connected  by  a  bar  is  also  applied  to  a  single  right  or  left  saddle  from 
which  a  bar  is  extended  to  the  other  side  of  the  arch  and  attached  to 
one  or  two  crowns  to  counteract  leverage.  When  a  saddle  on  one 
side  is  extended  from  the  cuspid  to  the  third  molar  the  necessity  for 
the  last  mentioned  application  of  a  bar  is  more  indicated. 

Connecting  Bars  to  Saddles. — Such  bars  are  generally  made  by 
burnishing  a  strip  of  pure  gold,  one-fourth  inch  or  less  wide,  then  bend- 
ing to  and  soldering  on  its  surface  with  hard  solder,  two,  three  or  more 
pieces  of  the  same  length  of  gages  18  to  20  gold  clasp  wire.     The 


GENERAL  APPLICATION  OF  REMaVABLE  BRIDGE-WORK      461 

gage  of  the  wire  and  the  number  of  pieces  are  to  be  regulated  by  the 
length  and  width  of  the  bar. 

The  following  method  minimizes  warping  and  insures  a  reliable 
bar:  Cut  a  strip  of  pure  or  platinized  gold,  gage  30,  of  the  required 
length,  one-fourth  inch  wide,  and  adapt  it  to  the  intervening  space 
between  the  saddles,  as  shown  at  A,  Fig.  984.     Cover  the  outer  surface 


B 

Pig.  984. 

of  the  gold  with  wax,  leaving  the  extreme  ends  exposed.  Invest  and 
remove  the  wax  with  boiling  water  and  trim  the  investment  so  as  to 
expose  its  surface  except  at  the  extreme  ends.  Place  pieces  of  gold 
clasp  wire  of  about  gage  20,  cut  one-fourth  of  an  inch  in  length,  evenly 
over  its  surface,  in  three  consecutive  rows,  with  one-sixteenth  inch 
interstices  between  the  ends,  as  shown  at  B.     When  ready  to  solder, 


Fig.  985. 

first  place  and  fuse  only  a  small  quantity  of  hard  solder  in  the  center 
and  then  gradually  diffuse  it  to  each  side  until  all  the  pieces  of  wire  are 
caught.  Next,  by  degrees  add  more  solder  and  shape  the  bar  to  the 
desired  form.  The  bar  is  then  trimmed  and  polished,  when  it  is  ready 
to  be  adjusted  and  united  to  the  saddles. 

Cast  Saddles  and  Plates. — The  formation  by  the  casting  method  of 
saddle  and;  plate  bridge  dentures  for  both  sides  of  the  mouth  connected 


462  CROWN;  BRIDGE-,  AND  PORCELAIN-WORK 

by  bars  is  considerably  practiced.  In  a  case  such  as  is  shown  in  Fig. 
968,  and  similar  ones,  the  wax  model  having  been  formed,  sprues  are 
placed  in  the  manner  illustrated  in  Fig.  985.  The  wax  pattern  is 
chilled,  removed  from  the  model  and  invested,  using  a  large  flask  and 
cast.  A  slight  space  should  be  provided  for  under  the  wax  bar  to 
allow  for  the  settling  of  the  denture  when  in  use. 

The  preferable  method  of  constructing  dentures  of  the  form  shown 
in  Fig.  969  is  to  first  cast  each  saddle  separately.  Position  each 
attachment  and  saddle  separately,  and  take  an  impression  with  pres- 
sure on  the  saddle,  remove,  invest  and  solder  attachment  to  saddle. 
Adjust  both  saddles,  take  an  impression  in  plaster  with  pressure  on 
the  saddles,  remove,  make  model  and  unite  the  saddles  with  a  con- 
necting bar  by  soldering.     (See  Part  I,  Chapter  VII.) 

The  formation  of  saddle  and  plate  bridges  with  the  clasps  and  lugs  or 
other  forms  of  attachments  all  in  one  casting  is  not  approved  by  the 
author,  for  the  reason  that  the  denture  will  rest  proportionately  more 
on  the  abutments  than  the  alveolar  ridge.  The  practice  of  scraping 
the  model  of  the  ridge  to  obtain  the  necessary  pressure  is  also  criticized, 
as  uniform  removal  of  the  surface  of  the  model  is  doubtful. 


CHAPTER  VII 

MANUTACTURED  ATTACHMENTS 

THE  ROACH  ATTACHMENT — METHOD  OE  APPLICATION — CONSTRUCTION 
OF  BRIDGE — THE  MORGAN  ATTACHMENT — REMOVABLE  BAR-BRIDGE 
ATTACHMENTS — THE  GILMORE  ATTACHMENT — SPLIT-BAR  BRIDGE 
ATTACHMENT — THE  CHAYES  METHOD  ANT)  ATTACHMENTS — THE 
PARALLELOMETER — THE  PARALLELODRILL — THE  ATTACHMENTS — 
THE  BUCCO-LINGUAL  ATTACHMENT — THE  UPRIGHT  ATTACHMENT 
— THE  DISTAL  EXTENSION  ATTACHMENT — CONSTRUCTION — SPLIT- 
POST     AND      BAR   ATTACHMENT 

To  simplify  the  construction  of  removable  bridge-dentures,  es- 
pecially of  the  saddle  or  plate  type,  several  styles  of  ready-made  attach- 
ments have  been  introduced  and  are  manufactured.  A  description  of 
the  most  used  of  such  attachments  will  be  here  given,  but  only  a  limited 
statement  respecting  their  application,  as  each  manufacturer  pubhshes 
directions  that  can  be  procured  on  application,  giving  such  information 
in  extensive  detail. 

The  Roach  Attachment^ 

This  is  one  of  the  simplest  of  the  manufactured  attachments.  It  is 
on   the   ball-and-socket  principle,  which  greatly  reduces  leverage  or 

A  BCD. 


Pig.  986. 

tipping  stress  on  the  supporting  teeth  and  obviates  accurate  parallehng. 
In  use,  while  the  denture  is  more  or  less  retained,  some  degree  of  mo- 
bility is  allowed.  It  may  be  classed  as  either  a  retaining  or  supporting 
abutment. 

1  Consolidated  Dental  Manufacturing  Co.,  agents  for  the  Roach  Attachment. 

463 


464  CROWN-,  BRIDGE-,  AND  FORC  EL  A  IN-WORK 

The  attachment  consists  of  two  parts  (Fig.  986),  a  round  slotted 
tube  of  gold  clasp  metal  (A) ,  into  which  fits  a  solid  ball  with  a  stem  for 
attachment  to  the  denture  (B). 

A  shoulder  set  on  the  stem,  close  to  the  socket  where  the  stem  enters 
the  slot,  furnishes  strength  and  acts  as  a  finishing  mark.  The  form  of 
the  socket  permits  settling  of  the  denture,  and  tightening  of  the  sides 
of  the  socket  on  the  ball  increases  retention. 

Method  of  Application. — Either  the  ball  or  the  socket  may  be 
attached  to  an  abutment  crown,  but  the  ball  portion  is  the  one  usually 
applied,  and  is  the  proper  one  to  connect  to  an  inlay  abutment.  The 
abutment  crown  is  adjusted  in  the  mouth  and  the  place  for  the  ball  or 
socket  marked  on  it.  The  spot  should  be  about  one-sixteenth  of  an 
inch  from  the  gum  and  towards  the  lingual  side,  sufficient  to  give  room 
for  proper  adjustment  of  an  adjoining  porcelain  facing  or  artificial 
tooth. 

The  locating  of  attachments  is  simplified  in  many  cases  by  taking 
an  impression,  which  removes  the  crown  or  inlay  in  position.  A  model 
is  then  made  and  the  attachment  located  on  it.  Cut  off  the  stem  to 
the  shoulder.  Guided  by  the  mark,  adjust  to  position  on  the  side  of 
the  crown,  invest  and  connect  with  solder.  For  strength,  a  more 
reliable  method  is  to  adjust  and  wax  to  the  end  of  the  stem,  a  small 
circular  piece  of  platinum  or  plate  as  shown  at  C  in  Fig.  986.  Invest 
and  attach  with  hard  solder,  then  adjust  and  wax  the  disk  to  the  side 
of  the  crown,  as  shown  at  D,  invest  and  solder  in  position. 

The  same  method  of  locating  and  soldering  the  stem  of  the  ball 
may  be  followed  with  an  inlay,  or  if  the  case  suggests  it,  the  stem  may  be 
shortened  and  placed  in  the  wax  model  of  the  inlay  and  united  in  the 
casting. 

In  cases  of  porcelain-faced  gold  crowns,  when  the  cap  is  con- 
structed, the  attachment  may  be  adjusted  and  connected  to  it  with 
hard  solder. 

Construction  of  Bridge. — The  impression  is  taken,  pressure  being 
exerted  on  the  saddle  or  plate  in  the  usual  manner  with  abutments  in 
position,  and  models  are  made.  The  sockets  are  placed  over  the  balls 
and  soldered  to  the  saddle  or  plate,  and  the  reverse  when  the  socket 
instead  of  the  ball  is  attached  to  the  abutment.  The  socket  when 
attached  should  be  left  exposed  on  one  or  both  sides,  so  that  it  may  be 
expanded  or  contracted.  During  the  construction  of  the  work,  it  is 
best  to  slightly  expand  the  socket  to  facilitate  removal.  To  tighten  it, 
use  pliers  and  insert  a  round  piece  of  wood  about  the  gage  of  the  ball 
to  avoid  over-contraction. 

The  best  method  of  uniting  the  socket  to  the  saddle,  is  by  the  use 


MAN  UFA  CTURED  A  TTA  CHMENTS 


465 


of  what  is  termed  a  contact  bar.  A  piece  of  gold  clasp  wire,  gage  No. 
15,  from  one-half  to  three-quarters  of  an  inch  long,  is  slightly  flattened 
on  the  side  that  is  to  go  next  to  the  socket  (A,  Fig.  987),  and  bent  at  a 
right  angle  so  that  it  will  rest  with  one  arm  against  the  side  of  the  abut- 
ment crown  and  the  other  on  the  surface  of  the  saddle.  The  socket  is 
next  fitted  over  the  ball,  the  side  of  the  bar  is  brought  in  contact  with 
the  side  of  the  socket  as  shown  at  B,  and  the  ball  and  socket  only  ce- 


FlG.  987. 

mented  together  with  wax.  The  bar  and  socket  are  removed,  invested 
and  strongly  united  with  hard  solder.  They  are  then  adjusted  in 
position  to  ball  and  saddle,  the  end  of  the  bar  attached  to  the  saddle, 
with  hard  wax,  bar  and  saddle  removed,  invested  and  securely  united 
with  solder.  When  in  use  the  end  of  the  contact  bar  resting  on  the 
side  of  the  abutment  crown  prevents  raising  of  the  end  of  the  saddle, 
but  does  not  interfere  with  its  compression  in  mastication. 


Pig.  988. 


Fig.  989. 


Fig.  988  shows  the  Roach  attachment  on  a  lower  denture  with  a 
connecting  bar  and  cuspid  and  bicuspid  as  abutments. 

Fig.  989  illustrates  another  style  of  Roach  attachment.  In  this 
form  the  ball  section  is  made  oval  and  fits  into  a  box  from  which  extends 
the  flange  A,  to  rest  on  the  abutment  and  act  as  a  contact  bar.  The 
flange  B  is  to  connect  the  attachment  to  the  denture. 


466 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 
The  Morgan  Attachment^ 


The  Morgan  attachment  consists  of  a  flattened  loop  of  clasp  metal 
called  the  keeper  (Fig.  990)  into  which  fits  a  two-winged  piece  called 
the  anchor  (Fig.  991).  The  keeper  is  soldered  to  the  abutment,  and 
the  shank  and  cover  of  the  keeper  to  the  denture. 


Fig.  990. 


Fig.  991. 


Fig.  992 


Fig.  993. 


Fig.  994. 


The  attachments  must  move  parallel.  A  paralleling  appHance 
called  a  jig  (Fig.  992)  is  used  to  parallel  and  also  to  hold  them  in  posi- 
tion while  being  soldered  to  the  abutments.  When  the  denture  is 
constructed  it  is  properly  secured  in  position  by  tightening  the  attach- 
ments sufficiently  to  increase  friction  of  their  parts.     Fig.  993  shows 

^  The  Morgan  Specialty  Co.,  Manufacturers. 


MA NUFACTURED  A  TTA CIIMENTS 


467 


the  Morgan  attachment  on  the  side  of  a  gold  collar  crown  with  porcelain 
facing,  and  Figs.  994  and  995  its  application  to  bridges. 


Fit..   995- 

Removable  Ear -Bridge  Attachments 

In  removable   bar   bridge   attachments,   the   bar  is   permanently 
attached  to  the  abutments  and  spans  the  space  between  them  inde- 


FiG.  996. 


Fig.  997. 


Fig.  958. 


pendent  of  the  bridge.  The  main  removable  portion  of  the  denture 
consists  of  either  a  bridge  or  a  plate  bridge  with  a  slot  or  countersunk 
base  that  contains  one  or  more  clamps  that  fit  over  and  lock  to  the  bar. 
This  form  of  construction  as  originally  introduced  is  illustrated  in 
Figs.  996  and  997,  which  show  an  upper  denture  of  this  style  as  made 


468 


CROWN-,  BRIDGE:,  AND  PORCELAIN-WORK 


by  the  late  Dr.  J.  Gardiner  Morey  in  1887,  originator  of  the  method. 
Fig.  998  illustrates  the  construction.  A  and  B,  Fig.  999,  are  side  and 
front  views  of  a  dummy  tooth  with  the  clamp  attachment;  C  shows 
the  bar  anchored  in  a  bicuspid  and  molar.  Fig.  1000  shows  the  denture 
in  position. 

The  Gilmore  Attachments.  ^ — These  are  manufactured  attachments 
for  this  style  of  work.     They  consist  of  an  assortment  of  clamps  made 


Fig.  999. 


Fig.   iooo. 


Fig  iooi. 


Fig.  1002. 


Fig.   1003. 


Pig.   1004. 


of  clasp  gold  to  fit  over  bars,  Fig.  looi.  They  are  made  of  platinized 
gold  for  attachment  to  gold  dentures  by  soldering  and  with  the  addition 
of  flanges  for  their  retention  when  used  with  vulcanite. 

The  abutment  roots  are  capped  with  a  plate  and  root  post  and  the 
teeth  are  capped  with  gold  crowns.  The  bar  to  support  the  clamps  is 
soldered  to  root-caps  and  gold  crowns,  as  seen  in  Fig.  1002.  The  ends 
of  a  bar  may  be  extended  beyond  the  abutment  root-caps  to  afford 
additional  space  on  the  bar  for  more  attachments,  as  seen  in  the  case 
of  a  lower  denture  in  Figs.  1003  and  1004. 

^  The  Detroit  Dental  Manufacturing  Co.,  Detroit,  Mich.,  Manufacturers. 


MANUFACTURED  A TTA CIIMENTS 
Split-bar  Bridge  Attachment^ 


469 


This  consists  of  a  manufactured  iridio-platinum  split  bar  with  a  V- 
shaped  flange,  as  shown  in  Fig.  1005,  that  fits  into  a  correspondingly- 
shaped  platinum  box. 

The  bars  are  made  in  four  sizes,  for  right  and  left  sides.  The 
angles  given  the  edges  of  the  bar  and  the  V-shaped  form  to  the  flange 


Fig.   1005. 


Fig.  2 


Pig.  3  *is-  * 

Fig.   1006. 


Fig.  1007. 

are  for  the  purpose  of  meeting  the  various  lines  of  natural  teeth  in  an 
occlusal  direction. 

Fig.  1006  shows  the  application  of  the  attachment  in  different  crowns. 

Fig.  1007  shows  a  partial  denture  with  this  attachment  applied  to 
a  bicuspid  and  tipped  molar. 

^As  devised  by  Mr.  H.  A.  Gollobin  and  Dr.  W.  A.  Bernstein.     Manufactured 
l)y  K.  A.  Gollobin,  no  West  40th  St.,  New  York. 


470 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


The  Chayes  Method  and  Attachments ^ 

In  this  method  the  intention  is  to  impart  a  sHght  resilient  mobihty 
to  the  denture  to  permit  it  to  respond  to  the  vibratory  as  well  as  mas- 
ticatory force  of  the  maxilla.  The  denture  is  formed  of  a  saddle  and 
retentive  abutments,  which  allows  direct  pressure  of  the  saddle  on  the 
membrane  of  the  alveolar  ridge  and  also  permits  a  slight  rotary-lateral 


Fig.   1008. 

motion  labio-lingually.     For  the  construction  of  dentures  of  this  style, 
the  following  described  instruments  and  attachments  are  used. 

The  Parallelometer. — Fig.  1008  illustrates  an  instrument  for  paral- 
leling abutments  and  their  attachments,  also  for  measuring  spaces. 
It  consists  of  two  sections  or  bars,  the  outer  one.  A,  into  which  sHdes 
the  inner  one,  B.  The  thumb  screw  C  extends  or  draws  back  the  inner 
section  B.     Fig.  1009  shows  the  instrument  extended.     The  body  of  the 


110   IjS  '210  Z|5  3{j  315  410 


Fig.   1009. 

instnlhient  is  40  mm.  long  and  it  can  be  extended  to  55  mm.  Each 
section  has  three  clamps,  marked  D,  E,  F,  G,  H,  I,  for  holding  in  place 
the  mandrels  for  carrying  the  attachments. 

The  Parallelodrill. — Fig.  loio  illustrates  a  right-angle  attachment 
for  the  denal  engine  with  sockets  for  two  drills  for  enlarging  or  drilling 
root-canals  in  parallel  Hues.  It  is  operated  in  conjunction  with  the 
parallelometer.     The  space  between  canals  is  measured  by  the  parallelo- 

1  As  devised  by  Dr.  Herman  E.  S.  Chaj^es  and  manufactured  by  the  Noemeteric 
Dental  Instrument  Co.,  17  West  45th  St.,  New  York. 


MA  N UFA  CTURED  ATTACH M EX TS 


471 


meter,  as  shown  in  Fig.  loii,  then  the  measurement  transferred  to  the 
parallelodrill  and  the  canals  enlarged,  as  shown  in  Fig.  1012. 


Fig.   ioii. 


Fig.   1012. 


The  Attachments.— The  attachments  consist  of  the  bucco-lingual, 
upright  and  the  distal  extension. 


472 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


The  Bucco-Lingual  Attachment. — This  is  formed  of  a  rectangular 
box  of  platinum  termed  the  "hood"  with  a  slot  in  the  side  facing  the 
bridge,  as  illustrated  at  A,  Fig.  1013.     The  anchorage  or  friction  sec- 
A  B  c 


Pig.  1013. 


Fig.  1014. 


tion,  B,  fits  into  the  "hood."  It  is  formed  of  a  strip  of  elastic  gold 
bent  and  doubled  in  the  form  of  a  T,  as  shown  at  B  and  C.  When 
the  arms  of  the  metal  forming  the  shank,  S,  Fig.  1013,  are  united  with 


Pig.  1015. 


Fig.  1016. 


solder,  the  anchorage  section,  B,  takes  the  form  of  a  flattened  post  with 
a  seam  in  the  center,  which  permits  it  to  be  expanded  and  tightened  to 
the  "hood."     The  shank  S  is  the  part  to  be  connected  to  the  bridge. 


Fig.   1017 


Fig.  X018. 


Fig.  1 014  shows  the  anchorage  inserted  in  the  hood,  and  Fig  1015 
the  "hood"  in  position  in  an  inlay  in  a  molar  with  the  anchorage  in- 
serted. 

The  Upright  Attachment.— This  consists  of  a  flat  spHt  bar,  as 
illustrated  at  A,  Fig.  1016,  that  fits  into  a  seamless  rectangular  tube,  B. 


MAN  UFA  CTURED  ATT  A  CHMEN  TS 


473 


It  is  intended  to  retain  the  end  of  a  bridge  on  a  bicuspid  or  molar  abut- 
ment, and  is  made  in  two  corresponding  sizes.  Figs.  1017  and  1018 
show  the  attachment  applied  to  a  molar  crown. 

The  Distal  Extension  Attachment. — This  attachment  is  illustrated 
partly  in  section  in  the  bicuspid  crown  in  Fig.  1019.     One  end  of  the 


Fig.  1019. 


Fig.  1020. 


bar  (A)  is  united  to  the  male  section  of  a  tube  and  split-post  inlay  at- 
tachment, in  a  right  superior  cuspid  and  the  other  end  is  inserted  into  a 
corresponding  socket  in  the  adjoining  bicuspid  crown,  or  a  dummy, 
where  it  is  anchored  with  a  screw  in  a  countersunk  cavity  (S).     An 


Fig.  1021. 


arched  form  is  given  a  portion  of  the  bar  to  allow  it  to  move  slightly  in 
the  socket  so  as  to  permit  a  similar  proportionate  movement  at  that 
end  of  the  bridge.  Fig.  1020  shows  the  attachment  on  the-side  of  an 
artificial  crown. 


474 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Construction.— Fig.    102 1   shows  a  case  with  these  attachments. 
In  the  construction  the  attachments  are  accurately  paralleled  when 


Fig.   1022. 


Fig.  1023. 


Fig.  I024. 


Fig.   1025. 


Fig.,  1026.  Pig  1027. 

Fig.    1026. — A,   shank  of  split  bar;  B,  split  post;  C,  platinum  box;  D   bottom  of  box. 

united  to  abutments  and  bridges.     Fig.   1022   shows  the  bridge    in 
position. 

In  the  finished  denture,  to  permit  the  bridge  to  yield  slightly  buc- 


MANUFA CTURED  A  TTA CHMEXTS 


475 


cally  and  lingually  as  well  as  vertically  under  the  stress  of  mastica- 
tion, the  sides  of  the  bucco-lingual  anchorage  (Fig.  1023)  are  slightly 
tapered  from  the  central  part  towards  the  ends. 

Fig.  1024  shows  the  Chayes  method  of  shaping  the  end  of  a  cuspid 
root  and  the  form  of  cap  applied.     Fig.  1025  illustrates  a  molar. 


The  Split-post  and  Bar  Attachment^ 

This  attachment  consists  of  a  combined  spUt  post  and  bar.     Fig. 
1026  shows  one  form  and  Fig.  1027  the  other.     The  split  bar  terminates 


Fig.   1028. 

with  a  spHt  post,  to  which  the  bar  acts  in  the  relationship  of  a  shank. 
The  combined  split  post  and  bar  fit  into  a  platinum  box  or  hood  which 
sits  in  the  abutment  inlay  or  crown.  The  end  of  the  split  bar  is  at- 
tached to  the  bridge. 

Fig.  1028  shows  two  hoods  of  the  form  shown  in  Fig.  1026,  being 
located  in  two  abutments  by  the  aid  of  a  specially  designed  parallelo- 
meter. Fig.  1029  shows  the  hoods  and  attachments  as  they  appear  in 
the  abutments,  and  above  them  the  ftnished  bridge  and  attachments. 

1  The  Combined  Split -post  and  Bar  Attachments  are  manufactured  by  Mr.  John 
Yirikian,  391  Central  Park,  West,  New  York,  from  whom  descriptive  details  of 
their  application  can  be  obtained. 


476 


CROWN;  BRIDGE-,  AND  PORCELAIN-WORK 


Fig.  1030  illustrates  the  other  form  of  this  attachment,  shown  in  Fig. 
1027,  in  a  bicuspid  and  molar,  and  in  a  completed  bridge. 


Fig.  1029. 


Fig.  1030. 

Fig.  1 03 1  shows  the  several  sizes  and  shapes  of  the  two  styles  of  the 
attachments.     To  allow  for  settling  of  the  denture  and  corresponding 


MANUFA CTURED  A TTA CHMEXTS 


477 


pressure  on  the  alveolar  ridge,  a  small  space  is  secured  under  the  split 
post  in  the  box  by  inserting  there,  as  indicated  at  E,  Fig.  1032,  a  very 


Li- 


(^ 


10 


O 


C_3 

CcS 


(E3 


c^ 


^ 


CE) 


r^ 


o 


<B 


small  flattened  bird  shot,  to  be  subsequently  removed  from  the  finished 
denture. 


PART  VI 
PORCELAIN  DENTAL  ART 


PORCELAIN  DENTAL  ART 
INTPODUCTION 

By  porcelain  dental  art  is  here  meant,  not  the  well-known  processes 
by  which  porcelain  teeth  bought  from  the  manufacturer  are  mounted 
on  metal  or  vulcanite  base,  but  the  actual  working  of  the  material  por- 
celain, from  the  mixing  of  body  and  colors  to  the  final  baking.  It  in- 
volves the  making  by  the  dentist  of  partial  crowns  (including  inlays) 
and  entire  crowns,  of  porcelain.  It  is,  in  some  degree,  a  return  to  the 
old  vogue,  when  the  dentist  made  the  porcelain  teeth  which  he  mounted 
for  his  patients;  but  the  present  practice  is  upon  a  much  higher  plane, 
in  which  the  artistic  is  one  of  the  principal  features. 

Porcelain  dental  art,  as  here  defined,  is  an  outgrowth  largely  of 
the  common  adoption  during  late  years  of  modern  methods  of  crown - 
and  bridge- work.  At  first,  its  possibilities  not  being  clearly  seen,  its 
application  was  confined  to  a  limited  field,  its  sphere  of  usefulness  widen- 
ing as  the  processes  became  better  understood  and  improvement  after 
improvement  was  brought  out.  Latest  methods  in  the  manipulation 
of  porcelain  seem  to  leave  Httle  further  that  can  be  accomplished  in 
special  operations,  so  far  as  artistic  merit  is  concerned.  It  is  by  no 
means  intended  to  be  suggested  that  the  processes  involved  in  porcelain 
dental  art  have  been  finally  perfected,  as  improvements  are  quite 
possible,  and  may  be  expected. 

The  successful  practice  of  porcelain  dental  art  is  not  easy,  as  will 
be  speedily  appreciated  by  those  who  enter  upon  it.  There  is  de- 
manded a  technical  and  manipulative  skill  and  a  judgment  equal  in 
degree  to  those  required  in  any  other  class  of  dental  operations,  a  fact 
which  will  serve  only  to  stimulate  the  attainment  of  perfection  in  its 
methods. 

In  presenting  the  subject  we  shall  deal  first  with  the  composition, 
properties,  and  methods  of  manipulating  the  porcelain  compounds  at 
present  in  use  in  this  line  of  work,  then  with  inlays  and  crowns. 


.31 


CHAPTER  I 

PORCELAIN  COMPOUNDS  OR  BODIES 

ingredients:  their  chemical  and  physical  character — LOW-  AND 
HIGH-EUSING  PORCELAIN  BODIES — COLORING  OF  PORCELAIN  COM- 
POUNDS—GUM ENAMEL — FOUNDATION  OR  BASAL  BODY — PREPARA- 
TION OF  PORCELAIN  BODIES — SELECTION  OF  THE  COLOR  OF  THE 
PORCELAIN  BODY — SAMPLE  SHADES — VARIATION  IN  SHADE^STA- 
BILITY  OF  SHADE  IN  USE — SPATULA  AND  BRUSHES  USED — PREPA- 
RATION OF  PORCELAIN  BODY  FOR  USE — USE  OF  GUM  TRAGACANTH  OR 
STARCH — APPLICATION  OF  PORCELAIN  BODY. 

Porcelain  Compounds  or  Bodies 

Ingredients:  Their  Chemical  and  Physical  Character. — The  re- 
quirements of  this  line  of  work  have  developed  a  demand  for  a  special 
class  of  porcelain  bodies  or  compounds,  made  up  of  ingredients  similar 
to  those  from  which  porcelain  teeth  are  made  and  to  those  commonly- 
used  for  continuous-gum  work,  but  differing  from  them  in  that  they  are 
lower  fusing,  are  very  finety  ground,  and  arranged  in  various  colors. 
Inlay-  and  crown-work  body  is  composed  of  silica,  silex — the  dioxid 
of  silicon;  feldspar,  a  double  silicate  of  aluminum  and  potassium; 
kaolin,  a  silicate  of  aluminum,  decomposed  feldspar,  and  a  mineral 
"flux,"  generally  composed  of  either  flint  or  Bohemian  glass  or  their 
compounds.  Flint  glass  is  made  of  silicate  of  potash,  or  soda  and  lead 
oxid;  Bohemian  glass,  of  a  silicate  of  potash  and  lime.  Glass  of  borax 
also  is  sometimes  used  as  a  compound  in  the  "flux." 

.  Silica  is  highly  infusible.  It  is  used  in  a  very  small  proportion  as 
the  foundation  ingredient  of  porcelain  to  assist  in  retaining  the  body  in 
shape  during  the  fusing,  and  imparts  structural  strength. 

Feldspar  is  quite  fusible.  It  forms  a  much  larger  proportional  part 
in  the  formation  of  porcelain  than  the  other  ingredients  combined. 
It  serves  to  agglutinate  the  particles  of  the  more  refractory  compounds, 
silica  and  kaolin,  and  imparts  a  semi-transparent  appearance  to  the 
porcelain. 

Kaolin  is  infusible  but  unites  with  feldspar  at  high  t'temperatures 
when  incorporated  with  it  and  is  an  element  of  strength.  It  is  used 
in  a  small  proportion  to  the  other  compounds  as  it  imparts  opacity 
to  the  porcelain. 


PORCELAIN  COMPOUNDS  OR  BODIES  483 

Flux  is  incorporated  to  modify  the  infusibility  of  the  other  in- 
gredients of  the  compound.  A  flux  of  the  character  of  flint  glass  is 
much  more  effective  in  lowering  the  degree  of  fusibility  of  a  porcelain 
body  than  one  of  Bohemian  glass  which  fuses  at  a  higher  degree.  Flint 
glass,  owing  to  the  presence  of  lead  oxid,  has  a  tendency  to  cause 
discoloration  of  the  porcelain  in  which  it  is  compounded  when  used  in 
the  mouth.  The  character  of  the  flux  and  the  skilful  proportioning  of 
it  to  the  other  ingredients  govern  the  fusibility,  while  maintaining  the 
other  characteristics  of  a  porcelain  body. 

Low-  and  High-Fusing  Porcelain  Bodies. — Porcelain  body  so  com- 
pounded as  to  fuse  below  the  melting  point  of  gold  and  so  permitting 
the  use  of  a  gold-foil  matrix  in  inlay-work  is  termed  "low-fusing." 
One  which  fuses  above  that  point  and  requires  the  use  of  platinum  for 
the  matrix  is  termed  "high-fusing." 

Coloring  of  Porcelain  Compounds. — Porcelain  compounds  are 
colored  to  imitate  the  shades  of  the  natural  teeth  by  thoroughly  in- 
corporating certain  proportions  of  titanium  oxid  and  preparations  of 
oxids  of  gold,  tin,  platinum,  iron,  cobalt,  uranium,  manganese,  silver, 
and  zinc.  The  exact  proportions  or  combinations  of  these  materials 
to  effect  the  desired  shades  in  the  different  preparations  of  porcelain 
bodies  is  a  matter  of  knowledge  and  skill  which  is  confined  to  the  indi- 
vidual manufacturers. 

Gum  Enamel. — Gum  enamel  is  composed  of  oxid  of  gold  (pur- 
ple of  Cassius),  feldspar,  and  flux.  The  proportion  and  character  of 
the  flux  incorporated  in  the  compound  regulates  the  f  using-point  in  this 
as  well  as  in  all  porcelain  enamels.  Gum  enamel  gives  surface  form  to 
an  artificial  gum  as  well  as  imparts  color.  It  fuses  at  a  slightly  lower 
heat  than  the  porcelain  it  is  applied  to.  In  this  respect  the  gum- 
enamel  used  in  the  manufacture  of  porcelain  gum  teeth  and  in  the  con- 
struction of  continuous-gum  and  porcelain  bridge-work  differs  from 
what  is  termed  pink  or  gum  color  stain,  which  latter  is  very  finely 
ground  and  fuses  at  a  comparatively  low  heat.  As  gum  enamel  fuses 
but  imperfectly  on  the  surface  of  platinum,  the  metal  has  to  be  first 
covered  with  a  layer  of  porcelain  body,  which  should  receive  what  is 
called  the  primary  bake  before  the  application  of  the  gum  enamel. 

Foundation  or  Basal  Body. — Foundation  or  basal  body  is  a  term 
used  to  design-'ate  a  preparat^qn  of  porcelain  body  that  is  applied  first 
to  form  the  base  or  foundation  of  an  inlay,  crown,  or  bridge.  The 
''Close"  porcelain  body  used  so  extensively  in  continuous-gum  work 
is  an  example  of  a  foundation  body. 

The  use  of  foundation  body  is  usually  confined  to  the  foundation 
or  internal  portion  of  the  work,  although  certain  parts  at  times  may 


484  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

be  entirely  constructed  of  it.  Any  moderately  high-fusing  porcelain 
body  may  be  used  as  a  foundation  in  association  with  one  fusing  at 
a  lower  temperature  applied  afterward.  A  foundation  body  is  gen- 
erally a  shade  darker  than  the  body  subsequently  applied  to  accord 
in  color  with  the  portion  of  the  work — the  dentin  of  a  tooth,  for 
instance — it  is  calculated  to  represent. 

Preparation  of  Porcelain  Bodies. — Porcelain  body  is  prepared  and 
sold  in  bottles  or  jars  in  a  set  of  about  twenty-five  different  shades, 
arranged  in  a  case,  such  as  is  shown  in  Fig.  1033,  accompanied  by  a  set 
of  samples  showing  the  colors  which  the  various  bodies  assume  when 
fused.  Some  sets  additionally  contain  a  bottle  of  gum  enamel  and  one 
of  foundation  body. 


Pig.  1033. 


Selection  of  the  Color  of  the  Porcelain  Body. — The  proper  color 
of  porcelain  body  should  be  selected  from  the  samples  while  the  tooth 
is  wet,  as  dryness  aflfects  the  shade.  In  inlay-work  for  approximal 
cavities  in  the  incisors  it  is  well  to  select  a  color  a  trifle  lighter  than  that 
of  the  natural  teeth,  as  shadows  and  the  cement  have  a  tendency  to 
darken  the  appearance  of  an  inlay.  Should  none  of  the  colors  shown 
by  the  samples  correspond  with  the  color  wanted,  it  is  customary  to  mix 
different  shades  of  the  porcelain  body  to  obtain  the  one  desired.  What- 
ever color  is  required,  first  ascertain  the  basal  color  and  to  this  add  the 
toning  material.  For  instance,  taking  yellow  as  the  basal  color,  a 
variety  of  shades  can  be  formed  by  the  addition  of  white,  others  still, 


PORCELAIN  COMPOUNDS  OR  BODIES 


48: 


by  the  use  of  blue,  and  so  on.  To  test  a  mixture  of  colors,  drop  a  small 
pellet  of  the  body,  say  about  the  size  of  an  intended  inlay,  on  a  piece  of 
blotting-paper  to  absorb  the  moisture,  and  bake  it  in  the  furnace. 
This  can  be  done  in  about  two  minutes,  and  will  positively  decide  the 
question  of  suitability.  Insufficient  fusing  will  render  the  porcelain  a 
trifle  darker  than  the  true  shade,  and  excessive  heat  will  lighten  it. 

Sample  Shades. — Special  sample  shades  can  be  made  at  different 
times,  and  the  formulas  entered  in  a  book  and  numbered.  Taking,  for 
instance,  of  the  S.  S.  White  colors,  which  are  lettered  from  A  to  Z,  one 
part  of  M  to  three  parts  of  G,  the  combination  may  be  numbered  IX, 
and  is  written  iM  +  3G  =  IX.  The  colors  are  mixed  to  a  doughy 
consistence  on  a  slab,  and  a  mold  made  of  fusible  metal,  such  as  is 
shown  in  Fig.  1034,  shghtly  oiled,  is  pressed  down  on  the  mass  and 
removed.  The  surplus  is  then  trimmed  at  the  edges  and  the  porcelain 
baked,  resulting  in  a  sample  such  as  is  shown  in  Fig.  1035.  A  simpler 
way  for  many,  though,  will  be  to  shape  the  mass  of  porcelain  on  aflat 


Fig.   1034. 


Fig.   1035. 


piece  of  platinum  plate,  approximating  the  form  shown  at  A  in  Fig. 
1035.  Flatten  one  end,  and  make  a  hole  with  an  instrument.  Flaws 
can  be  repaired  by  a  second  baking.  The  sample  shade  can  be  marked, 
as  shown  in  Fig.  1035,  in  Roman  numerals  with  a  disk.  If  the  point 
of  the  sample  is  ground,  as  shown  at  C,  the  indentation  can  be  covered 
with  oxyphosphate,  and  change  of  shade,  if  any,  will  be  exhibited. 

Variation  in  Shade. — A  difference  in  shade  between  the  region  of 
the  cervix  and  that  of  the  incisal  or  occlusal  section,  the  latter  being 
lighter  and  more  translucent,  is  characteristic  of  the  human  teeth. 
An  imitation  of  this  variation  of  shade  in  any  small  inlay  is  unnecessary, 
but  in  the  case  of  an  incisor  where  the  operation  involves  the  restoration 
of  a  large  part  of  the  side  of  the  tooth  including  the  incisal  edge,  it  is 
desirable.  To  effect  it  in  an  inlay,  the  same  method  is  practiced  as  in 
the  formation  of  American  artificial  teeth.  The  first  application  of 
body  to  form  the  upper  and  inner  section  is  made  yellowish  in  shade^  to 

^The  "Close"  body  when  used  for  this  purpose  should  be  ground  finer  than 
it  is  as  sold  by  the  manufacturer. 


486 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


imitate  the  dentin  of  the  tooth,  and  the  succeeding  ones,  es- 
pecially toward  the  incisal  edge,  of  lighter  and  more  trans- 
lucent shades. 

Stability  of  Shade  in  Use. — Stability  of  shade  in  use  is 
assured  in  high-fusing  porcelain,  while  change  is  liable  to 
occur  in  the  low-fusing  as  time  passes,  especially  should  the 
oxid  of  lead  be  used  as  an  ingredient  in  the  flux. 

Spatula  and  Brushes  Used. — A  small  tapering-pointed 
spatula  of  the  ordinary  form,  or  one  with  a  corrugated  handle 
for  the  purpose  of  vibrating  the  shank  or  handle  of  the 
appliance  supporting  the  work  during  the  application  of  the 
body,  is  the  most  suitable  (Fig.  1036).  Camel's-hair  brushes, 
such  as  artists  use  for  water  colors,  are  also  necessary.  They 
should  be  of  three  sizes,  the  smallest  for  carrying  and  applying 
the  mixed  body,  especially  small  portions  where  an  application 
or  addition  is  to  be  very  delicately  made,  to  some  desired  spot 
of  the  work;  also  for  whisking  an  edge  or  small  corner  free 
of  surplus  particles  of  the  body.  The  medium-sized  brush 
may  be  similarly  used,  or  in  the  same  manner  as  the  large 
size,  which  is  only  applied  dry  for  brushing  the  surface  of  the 
body  and  metallic  framework  to  free  it  from  particles  of  the 
body. 

Preparation  of  Porcelain  Body  for  Use.— In  the  prepara- 
tion of  porcelain  body  for  use  absolute  cleanliness  is  necessary, 
as  the  introduction  of  the  slightest  particle  of  foreign  matter 
is  liable  to  destroy  the  appearance  of  the  work.  The  required 
quantity  of  the  powder  is  placed  on  a  flat  or  slightly  concave 
glass  or  glazed  porcelain  slab  and  mixed  with 
distilled  or,  in  its  absence,  filtered  water,  applied 
from  a  drop,  or  pipette  bottle  (Fig.  1037).  The 
consistence  of  the  mixture  should  be  that  of  a 
soft  dough.  To  obtain  this  consistence  the 
surplus  moisture  can  be  absorbed  by  light 
pressure  of  the  corner  of  a  napkin  or  a  piece 
of  blotting-paper  against  the  body.  Alcohol 
is  directed  instead  of  water  for  mixing  the 
Jenkins  porcelain,  but  rapid  evaporation  is  all 
there  is  to  recommend  it,  and  this  is  an  objec- 
tion in  the  application  of  the  body  in  some 
styles  of  operations. 

Use  of  Gum  Tragacanth  or  Starch. — In 
contour  work  a  small  proportion  of  a  solution 


Fig.   1036.     Fig.   1037 


PORCELAIN  COMPOUNDS  OK  BODIES  487 

of  gum  tragacanth  or  starch  is  sometimes  added  by  operators  to  aid  in 
holding  the  particles  of  the  body  in  form  as  the  moisture  is  evaporated. 
Application  of  Porcelain  Body. — The  porcelain  body  is  carried  and 
positioned  on  the  work  with  the  pointed  portion  of  the  spatula  or  with 
brushes.  In  the  application  as  thorough  a  condensation  or  packing  of 
the  particles  as  possible  is  desirable.  This  is  best  effected  by  placing 
the  mixed  body,  of  a  dough-like  consistence,  a  little  at  a  time,  and  then 
precipitating  the  particles  by  vibration  by  tapping  the  shank  or  handle 
of  the  clamp  or  tray  holding  the  work  with  the  side  of  the  spatula  or 
by  drawing  over  it  the  corrugations  on  the  handle  of  one  such  as  is 
shown  in  Fig.  1036.  After  each  vibration  the  moisture  that  appears 
on  the  surface  is  absorbed  with  a  small  piece  of  blotting-paper.  The  fur- 
ther details  of  the  process  will  be  given  when  the  application  of  the  body 
to  the  different  forms  of  the  work  is  reached. 


CHAPTER   II 
FURNACES 

ELECTRIC — GASOLINE — GAS — USE  OF  FURNACES — ADVANTAGES  OF  THE 
ELECTRIC  FURNACES — DENTAL  FURNACE  PYROMETER 

Furnaces. — A  proper  furnace  is  essential  in  baking  porcelain. 
Small  electric,  gasoline  or  gas  furnaces  or  ovens  especially  designed  for 
use  in  connection  with  crown-  and  inlay- work  operations  are  the  styles 
used.  A  furnace  to  meet  all  the  requirements  for  general  work  should 
be  capable,  if  necessary,  of  generating  a  heat  approximating  3000°  F.,  as 
some  operations  in  porcelain  may  require  a  degree  of  heat  approaching 
that. 

Electric. — In  electric  furnaces  or  ovens  the  heat  is  generated  by 
means  of  the  resistance  of  fine  platinum  wire  coiled  free  of  contact 
around  a  fire-clay  muffle.  The  wire  is  embedded  as  it  encircles  the 
muffle  or  passed  through  small  channels  in  the  clay,  and  the  muffle  is 
enclosed  in  a  frame- work  of  fire-clay  or  iron  or  both  combined.  The 
electric  current  is  controlled  with  a  rheostat,  through  which  it  is  ap- 
plied gradually  in  heating  up  to  prevent  fusing  the  platinum  wire. 
At  first  the  handle  of  the  rheostat  should  not  be  moved  beyond  the 
first  button  for  at  least  one  minute.  After  that  it  may  be  further 
advanced  more  rapidly  on  the  other  buttons  until  the  required  heat  is 
generated.  The  platinum  wire  around  the  muffle  needs  to  be  renewed 
at  intervals,  the  necessity  for  renewal  depending  on  the  frequency  of 
use,  the  quantity  of  current,  and  the  care  exercised  in  its  application. 
Fig.  1038  illustrates  the  S.  S.  White  electric  furnace  of  a  size  suitable 
for  inlays  and  crowns. 

Gas. — Gas  furnaces  made  with  seamless  platinum  muffles  are  used 
in  preference  to  clay,  as  the  required  heat  can  be  obtained  in  them  in 
from  three  to  five  minutes.  A  platinum  muffle,  although  seamless, 
will  not  assure  against  the  gassing  of  porcelain.  Fig.  1039  illustrates 
the  ''Land  Midget  Gas  Furnace,"  operated  with  foot-bellows. 

Gasoline. — The  gasoline  furnace  is  now  being  given  preference 
over  the  gas  The  maintenance  of  heat  production  is  dependent  on  a 
pneumatic  pump.  The  muffle  is  made  of  either  fire-clay  or  nickel,  the 
latter,  of  which  the  Brophy,  illustrated  in  Fig.  1040,  is  an  example, 
being  preferred. 


FURNACES 


489 


Use  of  Furnaces.— The  gasoline  and  gas  furnaces  require  to  be  well 
heated  before  being  used.  This  is  necessary  to  rid  the  muffle  of  gas 
fumes  present  in  the  first  part  of  the  heating.  The  draft  should 
always  be  sufficient  to  entirely  consume  the  gas  and  carry  off  the  prod- 


ucts of  combustion.  If  this  is  neglected,  or  if  the  furnace  is  defective, 
gases  are  liable  to  penetrate  the  interior  of  the  muffle  and  affect  the 
color  and  character  of  the  porcelain  by  "gassing"  it,  a  condition  to  be 
corrected  only  by  substituting  new  materials.  In  the  use  of  electric  fur- 
naces, owing  to  the  purity  of  the  heat  generated,  this  precaution  is  not 


490  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Fig.  1039. 


Fig.   1040. 


FURNACES  491 

necessary.  The  work  may  be  safely  allowed  to  cool  gradually  in  any  of 
these  forms  of  furnaces  by  turning  off  the  heat  supply. 

For  fusing  porcelain  that  requires  a  heat  close  to  3000°,  a  gasoline 
or  gas  furnace  has  the  advantage  over  the  electric,  owing  to  the  fact 
that  such  a  degree  of  heat  in  time  burns  or  melts  the  wiring  of  the 
electric. 

Advantages  of  the  Electric  Furnace. — The  electric  furnace,  owing 
to  the  form  of  its  construction,  places  the  heat  under  perfect  control  and 
admits  of  its  accurate  regulation  by  the  pyrometer.  In  these  respects 
it  possesses  advantages  over  the  other  styles  in  use. 

Dental  Furnace  Pyrometer. — The  pyrometer  is  an  instrument 
that  indicates  the  degree  of  heat  in  the  muffle  by  a  needle  on  the  scale 
of  the  register.  By  its  aid  the  gradual  increase  and  exact  degree  of 
heat  are  determined  with  a  certainty  impossible  by  other  means,  and 
more  especially  by  the  eyes  in  such  small  muffles  as  are  used  for  porce- 
lain inlay  or  crown-work.  The  Fahrenheit  and  Centigrade  scales  are 
printed  on  the  register.  The  needle  that  registers  the  degree  of  heat  is 
operated  by  an  extremely  mild  current  of  electricity  generated  by  a 
thermo-electric  couple  inserted  through  the  back  of  the  muffle.  The 
couple  is  composed  of  platinum  and  rhodium  brazed  together.  It  is 
claimed  that  the  combination  of  these  two  metals  is  the  most  effective 
known  for  the  purpose.  The  instrument  shows  delicacy  of  construc- 
tion and  precision  in  registration.  When  the  furnace  is  in  use,  if  the 
door  is  opened  or  the  current  shut  off  for  a  moment,  the  change  is 
instantly  indicated  bv  the  needle  on  the  scale  of  the  register. 


CHAPTER  III 
FUSING  OF  PORCELAIN 

IMPORTANCE  OF  THE  OPERATION  OF  FUSING — SHRINKAGE — ^BAKING 
OR  FUSING — REQUIREMENTS  IN  BAKING — FIRST  BAKE — SECOND 
BAKE — FINAL  BAKE — COOLING  AND  ANNEALING  OR  TEMPERING 
OF  PORCELAIN — DIFFICULTY  ATTENDING  THE  PROPER  FUSION  OF 
SMALL  MASSES  OF  PORCELAIN  BODY — METHOD  USED  TO  INDICATE 
POINT  OF  FUSION — MERITS  OF  A  PYROMETER 

Importance  of  the  Operation  of  Fusing. — The  baking  or  fusing  of 
the  porcelain  body  is  one  of  the  most  important  factors  in  porcelain 
work,  as  the  result,  as  a  whole,  depends  on  its  successful  performance, 

Density,  strength,  shade,  and  surface  gloss  and  finish  are  affected 
by,  and  dependent  on,  the  proper  conduct  of  fusing. 

Too  rapid  heating  or  overheating  will  affect  the  density  and  strength 
by  causing  porosity  and  brittleness;  and  insufficient  fusion  will  impair 
its  crushing  strength  and  gloss. 

The  given  shade  of  any  porcelain  compound  depends  on  its  fusion 
at  exactly  the  heat  intended  for  that  special  preparation. 

Twenty-five  degrees  higher  or  lower  comparatively  lightens  or 
darkens  it. 

The  glaze  is  defective  if  insufficient  heat  has  been  applied,  and  a 
glass-like  appearance  is  imparted  to  the  edges  by  overfusing. 

Shrinkage. — All  porcelain  compounds  shrink  in  fusing.  The  tend- 
ency of  the  low-fusing  is  to  ball  or  assume  a  spherical  form,  and  of  the 
high-fusing  to  contract  from  the  edges. 

These  tendencies  are  attributable  to  the  proportion  and  especially 
the  character  of  the  flux  of  the  two  grades,  that  of  the  low-fusing  being 
largely  composed  of  the  component  parts  of  glass.  In  the  construc- 
tion of  work  most  of  the  shrinkage  occurs  in  the  first  fusing,  in  which  it 
ranges  from  about  40  per  cent,  in  the  low-  to  25  per  cent,  in  the  high- 
fusing. 

The  shrinkage  of  all  grades  of  porcelain  bodies  is  much  lessened 
by  a  thorough  condensation  or  crowding  together  of  the  particles  as 
they  are  applied  before  the  fusing. 

Baking  or  Fusing. — All  grades  of  body  require  at  least  three  bak- 
ings or  fusings  to  allow  the  several  shrinkages  which  occur  to  be  cor- 
rected and  to  effect  a  proper  vitrification  of  the  particles. 

492 


FUSING  OF  PORCELAIN  493 

The  first  fusing  is  termed  the  "biscuit  bake;"  the  first  and  second, 
"primary  bakes;"  and  the  last,  the  "final  bake." 

The  character  of  the  work  at  times  may  require  more  than  two  pri- 
mary bakes  before  it  is  ready  for  the  final  bake. 

Requirements  in  Baking. — In  the  first  bake,  and  likewise  in  all 
subsequent  ones,  the  work  should  be  first  slowly  heated  so  that  all 
moisture  in  the  freshly  applied  body  is  evaporated  by  degrees  and  not 
suddenly  forced  out  by  its  expansion  as  steam. 

If  such  care  is  not  taken,  particles  or  sections  of  the  body  are  liable 
to  be  loosened  and  misplaced  or  blown  off,  thus  impairing  the  form  of 
the  work  and  engendering  porosity.  The  work  should  be  first  set  on 
a  small  fire-clay  slab,  or  in  a  tray,  and  placed  on  the  shelf  a  little  to  one 
side  of  the  muflie,  and  very  slowly  heated  to  effect  evaporation  of  moist- 
ure, which  is  indicated  by  the  dry  and  lightened  shade  of  the  body.  It 
is  then  moved  to  the  center  of  the  shelf,  heated  by  degrees,  and  intro- 
duced into  the  muffle.  If  an  electric  furnace  is  used,  the  work  may  be 
placed  in  the  muffle  before  the  furnace  is  heated  and  the  electric  current 
connected,  the  voltage  gradually  increased,  and  the  work  allowed  to 
heat  up  with  the  muffle, — a  method,  however,  which  should  not  be  at- 
tempted with  a  gas  or  gasoline  furnace.  When  the  body  has  assumed 
a  red  heat,  it  may  be  moved  quickly  to  the  center  of  the  muffle  or  a 
trifle  beyond  it,  to  a  point  which  is  generally  the  center  of  the  greatest 
amount  of  heat. 

First  Bake. — In  the  first  or  "biscuit  bake"  the  body  for  inlay  or 
crown-work  should  be  fused  a  trifle  more  than  is  generally  accepted  as 
sufl&cient  in  the  corresponding  baking  of  porcelain  teeth  or  continuous- 
gum  work.  The  fusing  process  should  be  so  conducted  as  to  cause  the 
maximum  shrinkage  of  the  body  and  the  particles  to  become  solidly 
united,  but  with  the  mass  still  slightly  rough  and  glossy  on  the  surface, 
though  not  glazed.  To  accomplish  this  the  work  must  be  carefully 
watched  and  instantly  removed  at  the  proper  time  or  the  heat  shut  off. 
If  allowed  to  remain  in  the  furnace  until  the  fusing  point  is  reached, 
the  quality  and  appearance  of  the  porcelain  are  liable  to  be  impaired 
by  the  final  bake. 

The  heat  required  for  the  biscuit  bake  is  graduated  to  be  about  100° 
F.  for  the  low-  and  200°  F.  for  the  high-fusing  below  their  respective 
actual  fusing  points. 

Second  Bake.,- — For  the  second  bake,  the  shrinkage  which  takes 
place  in  the  first  is  compensated  by  the  application  of  additional  body, 
and  the  work  is  again  baked,  using  the  same  precautions  in  heating  as 
before. 

In  the  second  bake,  more  heat  may  be  appHed  than  in  the  first. 


494  CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 

In  the  case  of  a  low-fusing  porcelain,  the  heat  may  be  raised  to  within 
25°  to  50°  F.  of  the  actual  fusing  point,  and  in  the  high-fusing  to  within 
about  100°  F. 

Final  Bake. — For  the  final  bake,  body  is  again  applied  at  all  im- 
perfect points,  and  the  work  is  gradually  heated  until  the  actual  fusing 
point  of  the  body  is  reached.  It  is  then  allowed  to  remain  at  that  heat 
until  the  porcelain  assumes  a  smooth,  glazed  appearance,  when  it 
should  be  immediately  removed  or  the  heat  shut  off.  It  should  be  here 
noted  that  a  gloss  slightly  deficient  in  brilliance  is  preferable  to  an 
excessive  lustre,  as  the  former  can  be  increased  by  polishing,  if  desired. 
The  time  required  to  glaze  the  porcelain  after  the  fusing  point  is  reached 
is  about  ten  to  twenty  seconds. 

Cooling  and  Annealing  or  Tempering  of  Porcelain. — ^After  each 
bake,  and  especially  the  final  one,  the  porcelain  should  be  cooled  slowly. 
This  can  be  done  by  removing  the  work  from  the  furnace  and  inclosing 
it  in  a  cooling  muffle  or  by  placing  it  under  a  small  cover  to  protect  it 
from  the  air.  A  better  plan  in  the  final  bake  is  to  turn  off  the  heat  of 
the  furnace  and  allow  the  work  to  cool  in  the  muffle  until  the  red  glow 
has  disappeared  before  removing.  After  the  last  bake  the  porcelain 
is  annealed  or  tempered,  as  it  is  termed,  by  turning  off  the  heat  of  the 
furnace  and  allowing  the  work  to  slowly  cool  in  the  muffle  of  the  furnace. 
All  porcelain,  after  the  final  baking  and  cooling,  should  be  dipped  in 
water  before  handHng. 

Difficulty  Attending  the  Proper  Fusion  of  Small  Masses  of  Porce- 
lain Body. — In  the  baking  of  porcelain  body  of  a  size  such  as  is 
applied  in  continuous-gum  work,  the  process  of  fusing  can  be 
more  easily  watched  and  its  progress  more  surely  determined  than  in 
the  case  of  a  crown  or  inlay.  A  small  mass  of  porcelain  body  of  the 
size  of  an  inlay  is  more  quickly  affected  by  the  heat  than  a  larger  one. 
To  always  regulate  the  degree  of  heat  by  the  eye  alone  and  also 
determine  the  fusion,  especially  of  the  high-fusing  porcelain  body, 
in  such  cases  with  certainty  is  difficult  and  requires  extensive 
experience. 

Removal  of  the  work  from  the  muffle  to  examine  it  instantly  cools 
such  a  small  mass,  and  several  removals  for  inspection  are  very  in- 
jurious to  the  porcelain. 

Method  Used  to  Indicate  Point  of  Fusion. — The  melting  points  of 
gold  and  its  alloys  with  platinum  may  be  used  to  test  the  correctness 
of  the  scale  of  a  pyrometer  or  to  indicate  the  fusing  of  porcelain  com- 
pounds by  first  making  experimental  comparative  tests.  The  fusing 
point  of  the  metal  used  to  indicate  the  heat  requires  to  be  a  few  degrees 
below  that  of  the  body  for  the  biscuit  bake.     The  gold  or  its  alloy  is 


FUSING  OF  PORCELAIN  495 

fused  in  a  globule  and  then  flattened  out  on  an  anvil  with  a  hammer. 
The  metal,  after  being  tested  with  the  porcelain,  is  placed  upon  the  slab 
with  the  inlay  or  crown.  When  the  metal  assumes  the  spherical  form, 
which  can  be  seen  by  glancing  in  the  muflfle,  it  indicates  that  the  fusion 
of  the  porcelain  body  has  commenced.  The  globule  of  metal  can  be 
used  continuously  in  subsequent  bakings  by  flattening  it  out  each  time. 

Merits  of  a  Pyrometer. — The  introduction  of  the  use  of  a  pyrometer 
obviates  the  need  for  such  methods  as  are  described  above.  By  the 
pyrometer  the  progress  of  the  increase  of  the  heat  and  every  variation 
of  it  are  instantly  and  correctly  indicated  to  the  operator.  Any  degree 
of  heat  can  be  accurately  applied  and  regulated  for  any  specified  length 
of  time.  The  various  bakings  accordingly  can  be  conducted  so  as  to 
result  uniformly.  Doubt  and  uncertainty  regarding  fusing  are  re- 
moved and  the  work  simplified. 

In  baking  with  an  electric  furnace  associated  with  a  pyrometer, 
as  soon  as  the  work  is  placed  in  position  in  the  muffle,  the  door  is  closed 
and  it  is  hidden  from  view.  The  voltage  is  then  gradually  increased 
by  manipulation  of  the  rheostat,  and  the  progress  of  the  heat  is  indi- 
cated by  the  needle  on  the  scale  of  the  instrument.  When  the  needle 
has  registered  the  required  degree  of  heat,  the  current  is  shut  off,  the 
door  of  the  furnace  opened,  and  the  work  is  removed  or  allowed  to  cool 
in  the  furnace.  The  subsequent  and  final  bakes  can  in  like  manner  be 
given  without  variation  from  the  proper  degree  of  heat  and  time  required 
for  them,  without  once  opening  the  muffle  for  the  purpose  of  examina- 
tion. Chilling  of  the  work,  irritation  of  the  eyes  by  the  glare  and  heat 
of  the  muffle  through  opening  it  for  examinations,  and  loss  of  time  are 
consequently  avoided.  Irregularity  in  the  application  of  the  degree  of 
heat  in  the  fusion  of  the  body  of  porcelain  work  is  the  direct  cause  of 
a  large  percentage  of  failures.  Improper  conduct  of  a  primary  bake 
cannot  be  entirely  remedied  by  subsequent  fusings,  and  the  final  bake 
may  destroy  the  previous  part  of  the  work.  The  best  results  respecting 
strength,  appearance,  and  shade  in  the  use  of  any  particular  porcelain 
compound  can  only  be  obtained  by  fusing  it  at  the  degree  of  heat  spec- 
ially designated  for  it.  In  view  of  the  facts  presented,  the  introduction 
of  the  pyrometer,  especially  for  inlay  and  crown-work,  in  the  use  of 
high-fusing  porcelain,  was  an  important  innovation. 


CHAPTER  IV 

STAINING  OF  PORCELAIN 

CHARACTER    AND    PURPOSE    OF    MINERAL    STAINS — USE  OF    THE    COLORS 
— APPLICATION — GRADATION    OF    SHADE — FUSING 

Character  and  Purpose  of  Mineral  Stains. — Mineral  stains  are 
porcelain  enamels  colored  with  oxids  of  the  metals,  very  finely  ground, 
and  fusing  at  a  low  heat.  They  are  applied  to  reproduce  the  effect 
of  conditions  found  in  nature ;  as,  for  instance,  staining  of  edges  and  cusps 
to  assimilate  the  wear  through  mastication;  of  the  fissures  of  bicuspids 
and  molars  to  represent  the  discolorations  which  appear  in  these  places 
in  the  natural  teeth;  producing  variations  in  color,  such  as  the  darker 
shade  of  cuspids  when  compared  with  centrals  or  of  the  cervical  sur- 
face with  the  incisal  edge  or  occlusal  surface;  the  white  specks  often 
noticeable  in  the  natural  teeth;  and,  in  general,  the  modifying  or  darken- 
ing of  a  single  tooth  or  a  number  of  teeth. 

The  colors  of  The  S.  S.  White  Dental  Mfg.  Co.  are  brown,  yellow, 
gray,  blue,  white,  black  and  green,  and  pink  for  gum  shading  (Fig. 
1041).  By  combining  them  one  can  get  a  great  variety  of  shades. 
Mixing  brings  out  the  colors  very  nearly  as  they  will  appear  when  fired, 
the  firing  merely  intensifying  and  fixing  them.  By  the  skilful  applica- 
tion of  these  stains  artistic  effects  can  be  produced.  Their  successful 
use,  however,  requires  practice  and  care.  More  than  a  little  experi- 
mental work  is  necessary,  and  tests  on  a  discarded  tooth  should  first 
be  made,  as  it  takes  but  a  few  minutes. 

Use  of  the  Colors. — In  applying  the  stains,  if  the  tone  of  the  tooth 
is  yellow,  the  addition  of  brown  will  at  first  darken  the  yellow,  then,  as 
more  and  more  is  added,  bring  out  a  more  and  more  decided  brown. 

If  the  tone  is  blue  or  gray,  brown  at  first  merely  deepens  it,  but  on 
the  addition  of  a  considerable  quantity  produces  a  decided  brown. 

The  white  spots  frequently  seen  in  the  enamel  of  natural  teeth  can 
be  imitated  by  applying  a  thin  layer  of  white,  stippling,  and  firing  in. 

For  representing  the  wear  of  mastication  the  teeth  are  ground  and 
the  cutting-edges  and  fissures  stained  brown. 

Defects  in  the  enamel,  as  pits  or  grooves,  can  be  imitated  by  drill- 
ing out — use  a  diamond  drill  for  this — applying  the  color,  and  firing. 

A  combination  of  the  green  with  the  brown  will  give  a  natural- 

496 


STAINING  OF  PORCELAIN 


497 


looking  stain  similar  to  that  found  upon  the  teeth  of  inveterate 
"smokers." 

Inlays  or  crowns,  the  color  of  which  fails  to  match  their  surround- 
ings, in  some  cases  may  be  brought  to  the  desired  shade  by  the  addition 
of  the  proper  color  and  firing. 

Natural  "cutting-edge"  effects  may  be  obtained  by  using  either 
gray  or  blue  as  an  underglaze  color,  i.  e.,  after  applying  and  firing 
the  color,  cover  the  same  with  a  colorless  medium-  or  high-fusing 
porcelain  and  again  fire. 


Fig.  1041. 

The  pink  or  gum  color  will  be  found  useful  in  covering  platinum 
bands  which  are  exposed  below  the  gum  line,  also  in  coloring  that  por- 
tion of  an  inlay  which  lies  under  the  cervical  margin,  and  in  disguising 
the  necks  of  porcelain  teeth  whose  cervical  margins  are  above  or  below 
the  adjoining  teeth. 

Application. — The  enamel  stains  are  applied  with  a  small  brush 
and  evenly  distributed  over  a  given  surface  with  a  stippling  brush, 
both  of  which  accompany  the  outfit  of  stains.  The  colors  are  intended 
for  use  on  perfectly  fused  surfaces,  but  they  may  also  be  applied  after 
the  biscuit  bake  or  primary  bake,  and  the  tint  then  modified  by  the 
translucency  of  the  additional  body,  which  will  be  distributed  over  the 
part  for  the  subsequent  bakes. 

32 


498  CROWN-,  BRIDGE;  AND  PORCELAIN-WORK 

A  change  of  shade  of  only  a  part  of  a  facing  toward  the  incisal  edge 
in  the  construction  of  a  crown  or  dummy  may  be  effected  in  this  way 
by  the  appHcation  of  the  stain  to  the  palatal  side  of  the  porcelain. 

Gradation  of  Shade. — Gradation  of  shade  is  controlled  by  varying' 
the  thickness  when  laying  on  the  color.  This  can  be  effected  by  plac- 
ing on  the  color  with  the  small  brush  and  then  graduating  it  with  the 
stippling  brush.  It  can  also  be  done  by  wiping  the  color  off  with  the 
fingers.  To  effect  gradation  of  shade,  for  instance,  around  the  neck  of 
a  tooth  with  perfect  accuracy,  the  color  can  be  first  evenly  applied  to  the 
part  and  given  a  primary  bake.  The  surplus  color  toward  the  edge  is 
then  removed  with  a  sandpaper  disk,  making  it  gradually  lighter,  when 
the  final  bake  is  given  and  the  enamel  glazed. 

Fusing. — In  fusing  the  applied  mineral  stains,  place  porcelain  teeth 
with  the  pins  downward  on  a  fire-clay  slab,  or,  if  a  crown,  set  it  upright. 
Apply  the  heat  gradually  until  it  reaches  a  dull  red,  and  hold  it  at  that 
point  for  two  or  three  minutes.  Cool  gradually.  These  colors,  though 
glazing  at  a  low  heat,  will  well  retain  their  shade  when  fused  on  or 
with  porcelain  at  a  much  higher  point. 


CHAPTER  V 

CHARACTER  AND  SUITABILITY  OF  LOW-  AND  HIGH-FUSING 
PORCELAINS  FOR  INI.AY-  AND  CROWN-WORK 

REQXnREMENTS — COMPARATIVE     MERITS — FUSING     POINTS     OF     DENTAL 
PORCELAINS SUITABLE  APPLICATION  OF  EACH  GRADE 

Requirements. — The  value  of  the  respective  grades  of  porcelain 
for  the  work  in  hand  is  governed  by  their  imitation  of  tooth-substance, 
density,  strength,  permanence  of  structure,  retention  of  form  in  the 
process  of  fusing,  close  adaptation  of  the  finished  inlay  to  the  margin 
of  the  cavity,  and  lastly — a  most  important  factor — practicability 
in  application.  Porcelain  dense  and  strong  enough  for  use  as  an  ordi- 
nary labial  inlay  might  be  deficient  in  the  properties  requisite  to  the 
formation  of,  for  instance,  an  incisal  edge  for  an  incisor  tooth,  which 
would  demand  the  greatest  possible  strength  that  can  be  obtained  in 
porcelain.  Neither  would  porcelain  body  designed  to  form  an  incisal 
edge,  approaching  in  character  body  such  as  composes  porcelain  teeth 
— the  pulverized  porcelain  tooth  used  at  times  by  some  for  the  purpose 
requiring  a  most  intense  heat  to  fuse  it — be  as  suitable,  even  judged 
from  a  practical  standpoint,  for  forming  an  inlay. 

Comparative  Merits. — The  comparative  merits  of  low-  and  high- 
fusing  porcelain  for  the  work  in  hand  is  a  matter  as  to  which  consider- 
able difference  of  opinion  prevails.  This  is  probably  attributable  to 
the  fact  that  the  knowledge  or  experience  of  many  operators  is  confined 
in  a  measure  to  the  grade  they  have  in  use  and  the  methods  connected 
with  that  use.  Skilful  proportionment  and  preparatory  fusing  of  the 
various  ingredients  of  a  porcelain  body  realize  the  best  results  in  the 
fused  porcelain.  In  this  way  the  fusing  point  of  some  preparations 
may  be  lowered,  yet  their  comparative  qualities  be  maintained. 

Fusing  Points  of  Dental  Porcelains^ 

The  following  is  a  revised  list  of  the  fusing  points  of  the  present 
best  known  dental  porcelains: 

1  The  percentages  of  shrinkage  and  crushing  strength  in  pounds  given,  are 
the  results  of  a  series  of  experiments  made  by  Dr.  D.  O.  M.  LecCron. 

499 


500 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Percentages       Crushing 
°F  of  strength, 

shrinkage  pounds 

Asia  &  Sons  low-fusing 1550 

Ash  &  Sons  high-fusing 2012  34%  22.810 

Close's  foundation 22S8  21%  45.640 

Consolidated  Dental  Mfg.  Co.'s  foundation 2200  2x3'^  30.390 

Consolidated  Dental  Mfg.  Co's  Inlay 2138  31  15.080 

Jenkins'  Inlay 1580  38K  28.305 

Whiteley's  inlay 2200 

S.  S.  White  Dental  Mfg.  Co.'s  foundation 2400 

S.  S.  White  Dental  Mfg.  Co.'s  high-fusing 2300  233'-2  32-205 

S.  S.  White  Dental  Mfg.  Co.'s  medium 2200 

S.  S.  White  Dental  Mfg.  Co.'s  special 2560 

Suitable  Application  of  Each  Grade. — According  to  the  conditions 
discussed,  in  the  present  development  of  the  art  the  use  of  low-fusing 
porcelain  is  best  confined  to  inlays  at  labial  and  approximal  surfaces. 
It  is  inferior  to  a  moderately  high-fusing  porcelain  for  inlays  that  in- 
clude the  incisaledge  and  for  porcelain  and  platinum  crown- work,  where 
porcelain  nearly  analogous  in  structure  to  the  usual  artificial  crown  is 
required. 


CHAPTER  VI 

PORCELAIN  INLAYS 

THE  EARLIER  METHODS — MODERN  INLAYS  AND  THEIR  MERITS — INSTRU- 
MENTS AND  MATERIALS  USED  IN  THE  ADAPTATION  OF  MATRICES — 
PREPARATION  OF  CAVITIES — DIRECT  METHOD — FORMATION  OF  MA- 
TRICES FOR  LOW-FUSING  PORCELAINS — REMOVAL  OF  THE  MATRIX — 
INVESTING  THE  MATRIX  FOR  LOW-FUSING  PORCELAIN — PLATINUM 
MATRIX  FOR  HIGH-FUSING  PORCELAIN — TO  FACILITATE  THE  SHAPING 
OF  A  MATRDC — INDIRECT  METHOD — PROCESS  OF  SHAPING  A  MATRIX 
BY  A  MOLD  OR  DIE — REMOVAL  OF  THE  MATRIX — APPLICATION  OF 
PORCELAIN  BODY — THE  JENKINS  LOW-FUSING  BODY — USE  OF 
ELECTRIC  FURNACE  FOR  BAKING — METHOD  OF  FUSING — THE 
APPLICATION  OF  HIGH-FUSING  PORCELMN  BODY — FIRST  BAKE — 
SECOND  BAKE — FINAL  BAKE — COMPARATIVE  HEAT  OF  THE  FINAL 
BAKE — REMOVAL  OF  A  FOIL  MATRIX — PREPARATION  FOR  CEMENTA- 
TION— METHODS  OF  ETCHING  WITH  ACID  OR  A  DIAMOND — TO  AID 
ADJUSTMENT  IN  CEMENTATION — CEMENTATION — REQUIREMENTS; 
EFFECT    ON    COLOR    OF    PORCELAIN — OPERATION    OF  CEMENTATION 

The  Earlier  Methods. — The  first  operations  in  porcelain  inlays  or 
fillings  consisted  in  shaping  pieces  of  porcelain  as  nearly  as  might  be  to 
the  form  of  the  prepared  cavity,  into  which  they  were  then  cemented. 
These  inlays  were  cut  from  porcelain  teeth,  which  were  selected  to 
match  the  natural  teeth  into  which  the  inlays  were  to  be  inserted. 
Various  forms  of  inlays  were  then  put  upon  the  market  by  the  manufac- 
turers to  meet  the  needs  of  this  class  of  work,  which,  however,  never 
attained  any  special  prominence.  A  little  later,  slightly  tapering 
round  rods  of  porcelain  were  supplied  for  filling  labial  cavities  in  front 
teeth.  The  cavity  was  made  perfectly  round,  to  fit  the  end  of  a  rod 
corresponding  in  size,  which  was  fitted  tightly,  cut  off,  cemented  in 
place,  and  when  the  cement  had  set  was  trimmed  evenly  with  the 
surface  of  the  enamel  of  the  tooth.  This  latter  method  is  still  em- 
ployed, being  especially  adapted  to  very  small  cavities  on  the  labial 
surfaces. 

Then  we  had  glass  inlays,  of  which  a  number  were  brought  before 
the  profession,  but  they  failed  to  show  the  permanent  value  requisite, 
mainly  because  the  inlays,  besides  lacking  the  necessary  strength, 

501 


502  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

showed  a  decided  tendency  to  discolor  in  actual  service.  They  were, 
nevertheless,  an  important  step  in  the  progression  which  led  up  to  the 
modern  porcelain  inlay. 

Modem  Inlays  and  their  Merits. — The  porcelain  inlay  as  now  used 
is  a  dental  porcelain  fused  in  a  carefully  made  matrix  of  the  cavity  to 
be  filled,  of  the  exact  form  and  size  required.  The  two  grades  of  porce- 
lain for  inlay-work  are  the  low-fusing,  for  which  a  gold  or  platinum 
matrix  is  used,  and  the  high-fusing,  requiring  a  platinum  matrix. 
Their  respective  merits  for  inlay- work  have  been  much  discussed, 
without  deciding  the  difference  of  opinion  concerning  them.  The  char- 
acteristics of  both  and  the  methods  of  their  manipulation  and  their 
application  to  the  various  operations  will  be  impartially  presented. 

Properly  made  and  inserted  porcelain  inlays  afford  the  very  decided 
advantage  of  restoring  lost  tooth-structure  not  only  in  substance,  but 
in  appearance.  Porcelain  is  a  non-conductor  of  heat  and  electricity 
and  is  not  affected  by  oral  secretions.  In  these  respects  it  is  superior  to 
gold  as  a  filling  for  natural  teeth.  Porcelain  inlays  are  used  princi- 
pally on  the  labial,  buccal,  and  approximal  surfaces  of  teeth  from  bicus- 
pid to  bicuspid.  They  are  also  used  on  the  occlusal  surfaces  of  bicuspids 
and  upon  the  anterior  approximal  sides  of  molars  where  the  tooth  immedi- 
ately in  front  is  missing.  In  combination  with  the  cement  used  to  fix 
them  they  add  strength  to  a  frail  tooth  and  prevent  thermal  shock  in 
sensitive  cavities. 

The  first  requirement  in  a  porcelain  inlay  is  that  it  shall  accurately 
conform  to  the  shape  of  the  cavity,  with  an  absolute  fit  of  the  orifice 
and  side-walls.  The  cement  with  which  it  is  luted  fills  in  all  parts  of 
the  cavity  not  occupied  by  the  porcelain,  including  deep  recesses  and 
undercuts.  The  inlay  is  consequently  held  in  position  by  the  adhesion 
of  the  cement. 

In  cases  of  cervical  decay  extending  under  the  gum-margin,  the 
cavity  should  be  previously  packed  with  cotton  or  gutta-percha  and 
the  gum  pressed  from  its  normal  position  sufficiently  to  fully  expose  the 
edge  of  the  cavity  and  admit  of  the  perfect  adaptation  of  the  matrix  or 
the  taking  of  an  impression  for  a  model.  In  approximal  cavities  the 
teeth  should  be  previously  separated  well  apart — more  so,  as  a  rule, 
than  for  gold  filHng-operations — so  that  the  adaptation  of  the  matrix 
or  its  removal  shall  not  be  obstructed  nor  the  insertion  of  the  finished 
inlay  interfered  with  in  the  slightest  degree. 

When  the  decay  extends  on  the  root  further  under  the  gum  than 
it  is  desirable  to  extend  the  inlay,  the  cervical  section  of  the  cavity 
may  be  first  restored  with  a  gold  inlay  or  with  amalgam  (Fig.  1042) 
and  then  the  coronal  portion  shaped  and  inlaid  with  porcelain. 


PORCELAIN  INLAYS 


503 


Instruments  and  Materials  Used  in  the  Adaptation  of  Matrices. — 

Small-pointed  and  specially-shaped  burnishers  are  necessary  for  the 
proper  adaptation  of  matrices  to  cavities.  Fig.  1043  illustrates  a  set 
devised  by  Dr.  LeCron.  Nos.  i  and  11  are  for  general  use;  Nos.  2,  3, 
4,  5,  and  6  for  the  interior  of  cavities;  Nos.  7,  8,  9,  and  10  for  the  margin 
of  the  cavity  and  the  surface  of  the  tooth  combined.  Fig.  1044  shows 
ball-pointed  tweezers  for  carrying  pellets  of  spunk  or  cotton  used  to 
compress  the  foil  for  the  matrix  into  the  cavity  of  the  tooth.  They  may 
also  be  used  as  a  burnisher. 

Preparation  of  Cavities. — Cavities  for  porcelain 
inlays  are  prepared  about  as  for  gold  inlays,  as  described 
in  Part  III,  Chapter  XVII.  The  effort  should  be  to  give 
a  cup-shaped  formation  with  the  orifice  a  little  larger 
than  the  bottom,  so  that  the  matrix  of  gold  or  platinum 
when  adapted  to  the  cavity  can  be  removed  without  dis- 
turbing its  shape.  This  ideal  form  is  not  to  be  obtained  by  excessive 
removal  of  the  walls  or  enamel.  Unnecessary  cutting  away  of  tooth- 
substance  is  to  be  avoided.  When  the  decay  has  proceeded  in  such 
way  as  to  form  deep  recesses,  it  is  not  desirable  nor  necessary  to  cut 
away  the  tooth  to  make  the  ideal  cavity  form  include  them.  After 
removing  the  carious  portions  from  such  recesses,  they  can  be  filled 
with  cement  so  that  the  cup-shaped  form  for  the  matrix  shall  include 
only  the  main  cavity,  the  cement  where  it  joins  the  main  cavity  being 
dressed  to  conform  to  the  proper  contour.     The  exception  to  this  rule 


Fig.  1042. 


is  where  a  bar  or  horn-like  formation  of  the  porcelain  is  made  at  some 
point  as  an  anchorage  to  an  inlay  which  involves  restoration  of  the 
contour  of  the  working  surface  of  the  tooth,  as  of  an  incisal  edge.  If 
a  cervico-labial  cavity  is  given  a  slightly  oval  or  oblong  form,  with  one 
end  or  side  differing  somewhat  in  shape  from  the  other,  it  will  define 
the  exact  position  the  inlay  is  to  occupy  when  inserted  in  the  cavity. 
The  margins  should  be  trimmed  evenly  and  the  side-walls  inclined  at 
nearly  a  right  angle  to  the  line  of  the  enamel  surface,  especially  at  a 
point  where  the  force  of  mastication  is  to  be  withstood.     The  sur- 


504 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


rounding  edge  of  the  enamel  should  be  sharp  and  well  defined.     It  is 
well  to  polish  around  the  margins  inside  the  cavity  with  soft  iron 


Fig.  1044. 


Fig.  1049. 


Fig.   1050. 


burs  charged  with  diamond  dust,  or  with  points  of  Arkansas  stone 
kept  wet  during  the  polishing.     A  set  of  forms  such  as  are  illustrated 


PORCELAIN  INLAYS  505 

in  Fig.  437,  Part.  Ill,  Chapter  XVII,  are  suitable  for  the  purpose. 
The  use  of  sandpaper  disks  or  strips  across  the  surface  of  the  enamel 
should  be  avoided,  as  it  is  apt  to  make  a  coarse  joint. 

Figs.  1045,  1046,  1047  and  1048,  illustrate  teeth  with  prepared 
cavities  and  their  inlays  of  the  classes  commonly  involved  in  the  prac- 
tice of  porcelain  work. 

Fig.  1049  outlines,  in  section,  the  preparation  of  an  ordinary  cervi- 
cal cavity.  The  line  A  A  represents  the  prepared  cavity;  B  B  the 
point  where-  the  undercut — though  this  is  generally  better  omitted — 
may  be  made  when  the  porcelain  is  ready  for  insertion.  C  C  is  the 
gold  or  platinum  matrix.  Such  cavities  require  to  be  moderately  deep, 
in  order  that  the  inlay  shall  be  of  sufficient  thickness  to  overcome  the 
effect  of  the  cement,  which  would  otherwise  modify  the  shade,  owing 
to  the  translucency  of  the  porcelain.  A  cavity  of  this  character,  unless 
it  is  located  very  close  to  the  gum-margin,  being  one  of  the  simplest, 
is  generally  the  best  to  begin  practical  work  on. 

Fig.  1050  represents  a  typical  cavity  in  the  approximal  side  of  an 
incisor.  The  dark  point,  A,  in  the  sectionized  portion,  represents  a 
recess  in  the  cavity  made  necessary  by  extension  of  the  decay  in  that 
direction,  which  recess  must  be  filled  with  cement  to  give  proper  form 
to  the  matrix. 

In  an  approximal  cavity  sufficient  space  must  be  previously  secured 
by  some  preferred  method  to  permit  the  matrix,  after  it  has  been  per- 
fectly conformed  to  the  cavity,  to  be  lifted  out  without  disturbing  its 
form  in  the  least,  and  also  to  allow  the  porcelain  inlay  to  be  freely  in- 
serted. A  method  of  separation  of  the  teeth  to  provide  room,  which  is 
easy  for  the  patient,  is  to  apply  moderate  force  with  a  separator;  pack 
the  space  obtained  with  base-plate  gutta-percha  to  maintain  it,  and 
repeat  the  operation  at  intervals  of  a  few  days  until  sufficient  room  is 
obtained. 

In  the  upper  incisors,  when  a  portion  of  the  palatal  wall  can  prop- 
erly be  removed,  as  shown  at  A,  Fig.  1046,  less  space  is  required,  and 
removal  of  the  matrix  and  insertion  of  the  inlay  are  considerably 
facilitated. 

Direct  Method 

Formation  of  Matrices  for  Low-Fusing  Porcelains. — After  the 
cavity  is  prepared,  matrices  are  made,  especially  for  the  Jenkins  low- 
fusing  porcelain,  preferably  of  3^^00  0  platinum  instead  of  gold  foil 
No.  30  as  originally  directed.  The  foil  should  be  cut  round  or  oval, 
large  enough  to  cover  the  walls  of  the  cavity  and  extend  over  the  ad- 


So6 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


jacent  surface  of  enamel  one-fourth  of  an  inch,  more  or  less,  according 
to  the  location,  character  and  size  of  the  cavity,  to  permit  it  to  be  im- 
movably held  in  position  during  its  adaptation.  The  surplus  foil, 
when  shaped  to  the  contour  of  the  tooth  around  the  cavity,  serves  to 
outline  the  contour  to  be  given  the  inlay  when  the  porcelain  body  is 
inserted  in  the  matrix. 

The  platinum  foil  is  first  placed  in  the  palm  of  the  hand  and  the 
center  depressed.  The-  depressed  section  is  next  placed  in  the  cavity 
and  the  center  gently  brought  down  with  a  pellet  of  spunk  held  in  a 
pair  of  tweezers  (Fig.  1044),  or  when  necessary  by  a  ball  burnisher,  as 
No.  2  of  the  set  illustrated  in  Fig.  1043,  and  then  against  the  walls. 
Remove  the  spunk,  see  if  the  adjustment  of  the  foil  to  the  cavity  is 
satisfactory,  then  replace  the  spunk,  holding  it  in  place  with  the  left 
hand,  by  pressing  in  the  center  with  a  ball  burnisher.  Next,  with 
another  piece  of  spunk  held  in  tweezers  in  the  right  hand,  bring  down 
the  foil  over  the  edges  and  on  the  surface  of  the  enamel  around  the  cavity. 


Fig.   1051.  Pig.   1052.  Fig.   1053. 

Fig.   1053. — G  G  represents  line   of  gum-margin;    E,  line  of  foil  under  the  gum. 


and  burnish  it  with  a  burnisher,  such  as  No.  i  or  No.  11  in  Fig.  1043. 
In  the  adaptation  of  the  foil  to  the  cavity,  and  especially  for  holding,  it 
in  position  in  the  center  while  the  marginal  section  is  being  manipulated, 
the  author  has  found  that  a  wisp  of  cotton,  tightly  twisted  around  an 
old-fashioned,  long-handled  cavity  bur,  is  very  serviceable.  The  ball- 
pointed  tweezers  illustrated  in  Fig.  1044  are  recommended  for  this  part 
of  the  work.  The  foil  should  then  be  burnished  to  the  sides  and  margins 
of  the  cavity  and  over  the  surface  of  the  tooth  to  impart  the  greatest 
possible  amount  of  rigidity  to  it  before  its  final  removal.  In  a 
mesial  cavity  of  a  superior  central  the  foil  appears  about  as  illus- 
trated in  Fig.  1 05 1,  and  in  a  cervical  cavity  as  shown  in  Fig.  1053. 

The  foil  is  seldom  removed  and  annealed  during  its  adaptation. 
A  little  glycerin  may  be  applied  to  the  surface  of  the  gum,  enamel, 
and  cavity  to  prevent  adhesion  of  the  foil.  In  cases  where  the  cavity 
closely  approaches  to  or  extends  under  the  gum-margin,  rigidity  will 
be  imparted  to  the  portion  of  the  foil  placed  there  (see  Figs.  105 1  and 
1053)  by  folding  the  edge  over  before  adaptation,  as  shown  atLL,  in 


PORCELAIN  INLAYS  507 

Fig.  1052.  The  foil  when  adapted  should  be  so  positioned  that  a 
slight  space  will  exist  between  the  lap-over  edge  and  the  margin  of  the 
cavity,  about  as  is  also  shown  in  Fig.  105 1. 

Removal  of  the  Matrix. — The  removal  of  a  matrix  requires  most 
gentle  and  delicate  manipulation,  as  it  must  be  accomplished  without 
the  slightest  alteration  of  the  form.  On  account  of  its  greater  rigidity, 
platinum  foil  is  more  easily  removed  than  gold.  The  cavity  usually 
has  one  wall  inclined  slightly  more  than  the  others,  a  conformation 
which  is  easily  made.  The  matrix  is  best  loosened  at  the  extreme  edge 
of  the  burnished  surface.  The  removal  of  the  matrix  is  much  simplified 
and  alteration  of  its  form  prevented  by  filling  it  with  wax.  Soften 
and  roll  a  pellet  of  hard  tough  wax  a  trifle  larger  than  the  cavity,  place 
it  in  the  cavity  of  the  matrix  when  the  adaptation  is  completed,  and 
press  it  down  with  a  flat  burnisher  (No.  11,  Fig.  1043),  which  should  be 
covered  with  pulverized  soapstone  to  prevent  adhesion  of  the  wax  to 
the  instrument.  In  approximal  cavities,  the  pressure  is  best  exerted 
with  a  strip  of  tape  covered  with  the  soapstone.  The  pressure  should 
be  steady  and  exact.  The  wax  should  extend  over  the  edge  of  the 
cavity  onto  the  foil,  but  at  no  point  beyond  its  margin,  as  adhesion  of 
the  wax  to  the  tooth  will  interfere  with  the  removal  of  the  matrix.  A 
stream  of  cold  water  from  a  syringe  is  next  thrown  on  the  wax  and 
the  matrix  is  started  and  removed  from  the  cavity  by  the  insertion  of 
the  point  of  a  fine  instrument  in  the  center  of  the  wax.  The  wax  in 
the  case  of  a  platinum  matrix  can  be  removed  by  seizing  the  edge  of 
the  foil  with  tweezers  or  a  clamp  and  holding  it  open  end  downward  for 
a  moment  in  a  cup  of  water  that  is  simmering,  just  at  the  boiling  point, 
or  the  matrix  can  be  invested  in  marble-dust  and  plaster  and  the  wax 
removed  with  boiling  water. 

Should  either  gold  or  platinum  foil  tear  slightly  in  the  center  of  the 
cavity,  it  is  not  a  serious  matter,  as  the  porcelain  body  will  draw  from 
the  edge  in  the  first  fusing.  Platinum  foil  has  the  advantage  that  it 
can  be  adapted  to  the  surface  of  a  tooth  under  the  gum  margin  more 
easily  than  gold. 

Investing  the  Matrix  for  Low-fusing  Porcelain.^ — Mix  prepared 
non-shrinkable  asbestos  investing  material  with  water  to  the  desired 
consistence  and  place  enough  in  a  small  cup  or  tray  to  nearly  fill  it. 
Paint  the  under  side  of  the  matrix  with  a  little  of  the  material,  using  a 
camel's  -hair  brush,  and  place  the  matrix  on  the  center  of  the  investing 
material  in  the  cup.  Vibrate  the  cup  by  drawing  the  side  of  a  serrated 
instrument  against  the  side  or  edge  of  the  cup.  This  vibration  will  cause 
the  matrix  to  settle  in  the  investment.  See  that  the  investment 
material  covers  the  exposed  edge  of  the  platinum  (Fig.  1054).     Next 


5o8  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

place  the  investment  in  the  muffle  of  the  furnace,  slowly  evaporate  the 
water  and  burn  out  the  wax  in  the  matrix.  Remove  the  investment 
from  the  muffle  and  when  it  is  cold  tip  it  out  of  the  cup,  as  in  this  form 
it  is  more  easily  handled.  The  matrix  is  now  ready  for  the  application 
of  the  porcelain  body. 

Platinum  Matrix  for  High-Fusing  Porcelain, — Platinum  foil  Kooo 
of  an  inch  in  thickness  is  the  gage  usually  used  for  the  high-fusing  por- 
celain matrix.  To  render  the  platinum  soft  enough  for  the  purpose,  it 
should  be  previously  annealed  at  a  white  heat  in  the  muffle  of  a  gas 
furnace,  or  preferably,  on  a  piece  of  lime  in  an  electric  furnace.  An- 
nealed by  the  latter  method  it  becomes  nearly  as  soft  and  pliable  as 
gold.  A  direct  gas  flame  is  not  suitable,  as  the  desired  softness  cannot 
be  obtained  and  the  platinum  becomes  slightly  carbonized.  The  foil 
is  placed  across  the  cavity  and  cut  large  enough  to  extend  on  each  side 
a  little  more  than  if  gold  were  used,  so  that  it  can  be  held  securely  in 
position.  In  a  labial  cavity,  the  platinum  is  allowed  to  extend  over 
^,,,,===-=,,^^^^  the  surface  of  the  adjoining  teeth.     If  the 

/^^*^^.^^^V      cavity  is  on  the  side  or  at  the  incisal  edge, 
-_//       i^i\  Y\     the  foil  is  brought  over  on   the  labial  and 

'°'"^il         ^W  //     lingual  surfaces.     The  foil  is  carefully  and 

'^x.  yi       gently    pressed    into    the    cavity    in    such 

^^^^^^^^0        manner  that  it  shall  not  be  torn,  and  the  side 

portions  are  brought  down  in  position  against 
Fig.  1054.  ,  .  .    ,  ,  ^,.   .    .        *       , 

the  surface  of  the  tooth  or  adjoining  teeth. 

While  being  firmly  held  in  position,  the  foil  is  carefully  adapted  to  the 

cavity  by  burnishing.     This  process  is  begun  at  the  edge  of  the  cavity 

with  a  circular  motion  of  the  burnisher  around  the  margins.     As  the 

platinum  sinks  into  the  cavity,  the  metal  is  gradually  brought  down 

against  the  sides  and  finally  in  the  center.     If  the  metal  were  first  pressed 

down  in  the  center,  as  gold  foil  is,  the  platinum  would  be  torn  to  an 

extent  that  would  ruin  it  as  a  matrix.     At  this  stage  of  the  formation 

of  the  matrix,  if  desirable,  the  foil  is  removed,  annealed,  replaced  in 

the  cavity  and  then  burnished  to  the  edge  and  surface  of  the  enamel 

and  removed.     Before  finally  removing  the  matrix,  it  is  advisable  to 

uniformly  compress  its  entire  surface  to  the  walls  of  the  cavity  and 

adjacent  surface  of  the  tooth  to  remove  any  slight  spring  or  warping 

should  such  exist.     This  is  done  by  introducing  into  the  cavity  and 

placing  over  the  surface  of  the  tooth  pieces  of  spunk  and  pressing 

uniformly  at  the  same  time  on  the  entire  mass.     It  may  be  done  also 

by  stretching  a  piece  of  rubber-dam  tightly  over  the  foil.     The  spunk 

is  first  removed  and  then  the  foil  carefully  started  at  the  edges  and 

lifted  from  the  cavity. 


PORCELAIN  INLAYS  509 

To  Facilitate  the  Shaping  of  a  Matrix, — To  facilitate  the  shaping  of 
either  a  platinum  or  a  gold  matrix,  place  the  foil  on  the  surface  of  a 
piece  of  soft  fine-grained  cork  and  with  a  ball-shaped  burnisher  press 
the  center  into  the  cork  and  give  the  foil  a  cup-shape  form  approximat- 
ing that  of  the  cavity.  A  slit  in  the  foil  at  about  the  point  A,  Fig. 
1046,  but  not  extending  into  the  cavity,  is  also  suggested  but  preferably 
avoided. 

Indirect  Method 

Process  of  Shaping  a  Matrix  by  a  Mold  or  Die. — An  impression  is 
taken  of  the  cavity  and  an  amalgam  die  made.  The  process  of  matrix 
formation  for  both  high-  and  low-fusing  porcelains  is  the  same.  The 
platinum  foil  is  cut  round  or  oval  in  form,  the  center  depressed  in  the 
palm  of  the  hand  and  then  placed  in  the  central  or  deepest  section  of 
the  cavity.  The  center  of  the  foil  is  first  compressed  by  two  or  more 
successively  applied  pellets  of  spunk  with  ball-pointed  tweezers  (Fig. 
1044).  The  spunk  is  removed  and  the  platinum  burnished  into  all 
the  grooves  and  depressions,  preferably  with  a  round-pointed  glass 
burnisher.  The  matrix  is  next  filled  with  pieces  of  spunk,  the  spunk 
held  in  position  at  the  edges  of  the  cavity  and  surface  of  the  form  of 
the  tooth.  The  whole  is  now  placed  in  a  swager,  covered  with  a  disk 
of  rubber-dam,  and  swaged.  The  spunk  is  removed  from  the  matrix 
and  the  platinum  thoroughly  burnished  with  the  glass  burnisher,  the 
spunk  replaced  and  the  matrix  again  swaged. 

Removal  of  the  Matrix. — The  spunk  is  removed  and  a  pellet  of 
hard  wax  sufficient  to  fill  the  cavity  of  the  matrix  and  extend  well 
over  the  edge  and  on  the  surface  nearly  to  the  margins  of  the  platinum, 
is  melted  and  dropped  in.  A  piece  of  fine  iron  wire  is  hooked  on  the  end, 
heated  and  inserted  into  the  center  of  the  wax,  the  wax  chilled,  the 
platinum  started  at  the  edges  and  the  matrix  lifted  from  the  mold  by 
the  aid  of  the  wire.  If  the  matrix  is  of  3^^000  platinum,  it  is  invested  as 
already  described. 

Application  of  Porcelain  Body.^ — The  methods  of  procedure  in 
applying  the  body  with  low-  and  high-fusing  porcelain  are  quite  similar, 
irrespective  of  the  degree  of  heat  required.  A  description  of  the  use 
of  one  style  will  practically  explain  the  subject  for  both. 

The  Jenkins  Low-Fusing  Body. — This  is  a  porcelain  introduced  by 
the  late  Dr.  N.  S.  Jenkins,  formerly  of  Dresden,  Germany.  As  indi- 
cated by  the  pyrometer  it  fuses  at  1580°  F.  It  forms  a  dense,  hard 
porcelain  with  a  considerable  degree  of  crushing  strength,  and  resem- 
bles in  appearance  the  porcelain  of  an  EngUsh  tooth  more  than  that 


5IO  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

of  the  American.  The  following  is  an  explanation  of  the  use  of  the 
Jenkins  porcelain  and  the  appurtenances  connected  with  it.  Place  upon 
a  palette  the  required  quantity  of  the  body  of  the  selected  color  and 
mix  with  distilled  water.  With  the  small  thin  blade  of  the  spatula, 
carry  the  body,  well-moistened,  into  the  matrix  and  fill  it  up  to  but 
not  over  the  edges.  During  the  packing  aid  the  precipitation  of  the 
particles  of  the  body  by  a  few  light  taps  on  the  side  of  the  investment. 

Use  of  Electric  Furnace  for  Baking. — The  heat  is  gradually  raised 
to  a  point  considerably  below  the  fusing  point  of  the  porcelain  and 
then  increased  by  degrees,  as  required.  The  work  being  exposed,  the 
process  of  fusing  is  seen  and  determined.  With  a  pyrometer  the  heat 
can  be  accurately  defined  and  the  fusing  of  the  porcelain  conducted 
without  the  expertness  required  for  the  purpose  without  it. 

As  the  Jenkins  porcelain  fuses  at  about  1580°  F.,  the  primary  bakes 
can  be  made,  guided  by  the  pyrometer,  at  1480°  to  1500°  F.,  and  for  the 
final  one  the  heat  can  be  raised  to  1580°  F.,  at  which  degree  it  should  be 
held  for  about  ten  seconds,  when  the  current  should  be  turned  off 
instantly. 

Method  of  Fusing. — Place  the  investment  containing  the  matrix 
on  the  shelf  on  the  furnace  in  front  of  the  muffle  and  slowly  evaporate 
the  moisture.  This  should  not  be  done  hurriedly,  as  the  moisture  must 
be  evaporated,  not  boiled  out.  Next  move  the  investment  by  degrees 
into  the  muffle  and  gradually  increase  the  heat. 

The  process  of  fusing  can  be  clearly  seen  in  the  muffle.  When  the 
mass  begins  to  fuse,  hold  the  heat  but  do  not  try  to  accelerate  the 
melting  by  rapidly  increasing  it.  When  the  work  approaches  the  fusing 
stage,  the  fact  is  indicated  by  a  dark  shade  which  for  a  moment  passes 
over  the  porcelain  body,  caused  probably  by  combustion  of  a  small 
quantity  of  gum  introduced  as  an  ingredient  to  assist  in  holding  the 
particles  of  the  compound  together.  The  body  then  again  assumes  a 
light  shade,  and  at  about  a  red  heat  fuses  sufficiently  for  a  primary  bis- 
cuit bake,  when  the  application  of  heat  must  be  stopped  instantly. 
To  cool  the  investment,  remove  it  or  shut  off  the  current.  When  a  cup 
is  used  to  hold  the  investment,  the  cooling  can  be  hastened  by  placing 
the  bottom  against  the  surface  of  cold  water,  but  care  must  be  taken 
that  the  water  does  not  enter  the  cup.  In  the  first  fusing  the  body 
globulates  and  contracts  nearly  one-half  of  the  size  of  the  cavity  of  the 
matrix,  a  characteristic  of  low-fusing  bodies.  The  fused  body  in  the 
matrix  is  moistened  with  water  and  more  body  is  applied  to  fill  the 
vacancy  caused  by  the  shrinkage.  If  the  investment  is  wet  with  the 
water  in  the  application,  it  will  not  injure  it. 

For  the  second  bake  heat  up  the  investment  and  body  slowly  as 


PORCELAIN  INLAYS 


before  to  evaporate  the  moisture  and  then  give  the  porcelain  body  an- 
other biscuit  bake. 

A  third  application  of  body  is  necessary  for  exactness  of  edges  and 
contour.  In  the  third  or  final  bake,  the  heat  is  carried  higher  than 
in  the  previous  ones,  up  to  the  actual  fusing  point  of  the  porcelain  body, 
a  "glazing  heat,"  to  impart  a  glossy  surface.  It  is 
well  to  examine  the  inlay  with  a  magnifying  glass,  to 
be  sure  that  the  edges  are  exact,  both  in  applying  the 
body  and  after  fusing.  The  tendency  on  the  part  of 
the  operator,  in  the  beginning,  is  to  build  out  too 
much,  but  after  some  experience  he  learns  to  get 
exactly  the  form  and  fullness  desired.  After  the  final 
baking  it  is  better  to  let  the  piece  cool  somewhat 
slowly. 

The  Application  of  High-Fusing  Porcelain  Body. 
The  application  of  high-fusing  porcelain  body  to 
platinum  matrices,  though  similar  to  that  described 
in  relation  to  low-fusing,  differs  in  important  minor 
details.  The  shade  of  body  selected  is  wet  with  dis- 
tilled or  filtered  water  and  dried  with  blotting-paper 
to  the  consistence  of  a  paste.  The  matrix  may  be  in- 
vested or  not.  If  not  invested,  it  is  held  by  the  edge 
with  pliers  or  clamp-tweezers.  (See  Fig.  1055.)  The 
porcelain  body,  of  a  dough-like  consistence,  is  carried 
on  a  spatula,  or  preferably  the  point  of  a  very  small 
camel's-hair  brush,  a  portion  at  a  time,  and  dropped 
in  position  in  the  matrix,  and  by  sharp  taps  on  the 
back  of  the  tweezers,  or  by  vibrations  caused  by 
drawing  the  corrugations  on  the  handle  of  the  spatula 
shown  in  Fig,  1036  across  them,  the  body  is  settled 
down  in  the  matrix.  This  tapping  or  vibrating  packs 
the  particles  of  porcelain  closely  together  and  sends 
the  moisture  to  the  surface  at  each  tapping,  when  it 
should  be  absorbed  with  a  piece  of  blotting-paper 
trimmed  to  a  point.  Through  this  condensation  of  -pic.  1055. 
the  porcelain  body,  the  shrinkage  which  naturally 
occurs  in  the  baking  is  reduced  to  the  minimum,  and  porosity  is 
avoided.  The  first  application  of  body  should  not  be  allowed  to  come 
quite  to  the  edge  of  the  cavity  of  the  matrix.  The  matrix  if  not  in- 
vested is  set  on  a  bed  of  silex  on  a  small  fire-clay  slab. 

First  Bake. — The  slab  is  placed  on  the  shelf  in  front  of  the  muffle 
to  evaporate  the  moisture  from  the  body.     It  is  then  slowly  advanced 


512  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

into  the  mufBe  and  the  body  given  the  primary  bake,  which  should  be, 
as  gaged  by  the  pyrometer,  from  150°  to  200°  F.  below  the  actual  fus- 
ing-point  of  the  make  of  porcelain  body.  Some  high-fusing  compounds 
fuse  nearly  200°  or  more  above  others.  The  primary  bake  under  such 
condition  must  be  calculated  accordingly,  or  determined  by  testing. 
The  heat  should  be  only  sufl&cient  to  well  unite  the  particles  and  give 
the  body  a  slight  glaze.  In  this  primary  bake  considerable  shrinkage 
takes  place.  The  larger  the  matrix,  the  more  noticeable  the  shrinkage 
will  be. 

Second  Bake. — The  matrix  is  again  placed  in  the  cavity,  and  while 
firmly  held  in  position  by  pressure  exerted  on  the  center  of  the  porcelain, 
the  platinum,  which  is  always  slightly  drawn  from  the  margins  by  the 
contraction  of  the  porcelain,  is  reburnished  at  the  edges  of  the  cavity. 
In  this  second  burnishing  the  platinum,  which  is  then  extremely  soft 
from  the  annealing  it  received  in  the  baking  of  the  body,  is  additionally 
thinned  at  the  margins  of  the  cavity  and  is  adapted  with 
r^  (  j  great  accuracy.  More  body  is  applied,  filling  the  matrix  to 
the  edge,  and  a  second  bake  given  at  a  heat  a  few  degrees 
higher  than  the  previous  one. 

Final  Bake. — For  the  final  bake  all  new  imperfections 
in  the  porcelain  are  filled  in  and  a  heat  applied  sufficient 
to  perfectly  coalesce   the   particles  and  give   the  work  a 
uniform  glazed  surface.     For  this  final  bake  the  heat  should 
be  run  up  exactly  to  the  fusing-heat  of  the  porcelain  and 
Fig.  1056.    maintained  there  for  from  fifteen  to  twenty  seconds,  and 
then  instantly  shut  off  and  the  work  gradually  cooled. 
Comparative  Heat  of  the  Final  Bake. — Should  the  circumstances 
require  more  than  two  primary  bakes,  the  full  fusing-heat  of  the  porce- 
lain should  be  avoided  until  the  final  one. 

Removal  of  a  Foil  Matrix. — When  the  inlay  is  cool,  always  first 
wet  it  with  water  before  handling,  then,  if  invested,  remove  it  from  its 
investment.  With  tweezers  gently  and  slowly  bend  back  the  foil 
from  the  edges  and  it  will  usually  strip  off  in  one  piece.  If  any  shreds 
of  foil  adhere  to  the  inlay,  remove  them  with  a  fine  excavator. 

Preparation  for  Cementation. — For  the  purpose  of  retention  of 
inlays,  a  few  grooves  are  made  on  the  bottom  and  sides  of  the  porcelain 
with  a  small  diamond  disk  (see  Fig.  1056),  or  the  gloss  removed  with  a 
very  small  cone-shape  carborundum  point  to  facilitate  adhesion  of  the 
cement. 

Methods  of  Etching  with  Acid  or  a  Diamond.^ — If  the  inlay  is  too 
small  to  handle  conveniently,  the  gloss  can  be  removed  by  covering 
the  face  and  margins  of  the  base  with  wax  and  applying  hydrofluoric 


PORCELAIN  INLAYS  513 

acid  for  a  few  minutes.     An  inlay  can  be  quickly  etched  over  the  entire 
surface  except  along  a  line  at  the  extreme  edge  where  it  meets  the 
margin  of  the  cavity,  with  a  diamond  point  in  the  engine  hand-piece, 
aided  by  a  lens  to  magnify  the  part.     The  lens,  for  convenience,  should 
be  mounted  on  a  stand  like  that  used  by  wood  engravers.     By  this 
method  nearly  the  entire  cavity-surface  of  the  porcelain  is  divested  of 
its  glaze  and  roughened.     The  adhesion  of  the  cement  to  such  a  surface, 
which  is  much  more  porous  than  when  merely  acted  on  by  hydrofluoric 
acid,  is  absolute,  and  displacement  of  the  inlay  from  lack  of  attachment 
of  the  cement  is  well  assured  against.     Excessive  and  deep  indentation 
of  an  inlay  with  disks  weakens  it  and  renders  it  liable  to  fracture  in 
insertion  or  use.     In  shallow  inlays  it  is  liable  also  to  afifect  the  shade. 
To  Aid  Adjustment  in  Cementation. — In  the  cementation  of  an 
inlay  it  is  well  to  be  able  instantly  to  insert  it  correctly  in 
the  cavity,  as  its  removal  and  reinsertion  after  the  cement        i\ 
is  applied  are  objectionable.     The  inlay  after  the  fitting  is       mWk 
completed  may  be  laid  upon  the  operating  case  in  such      m  % 
wise  that  there  will  be  no  uncertainty  in  carrying  it  straight     m^'^^ 
to  its  correct  position.     Another  way  is  to  insert  the  inlay    fs^^j 
before  the  cement  is  applied,  and  after  drying  the  surfaces    |gi|pill 
mark  corresponding  parts  of  tooth  and  inlay  with  a  fine-   „ 
pointed  pen,  drying  the  ink  with  hot  air.     (See  Fig.  1057). 
The  marks  form  an  unerring  guide  to  the  proper  relative  position  of 
the  inlay.     A  few  grooves  may  be  made  in  the  walls  of  the  cavity  to 
favor  the  cement,  but  this  is  not  always  considered  necessary. 

Cementation 

Requirements:  Effect  on  Color  of  Porcelain. — Oxyphosphate 
cement  is  almost  universally  used  for,  the  cementation  of  porcelain 
inlays.  Its  adhesiveness  to  both  tooth-structure  and  unglazed  porce- 
lain renders  it  most  suitable  for  the  purpose,  but  its  solubility  at  the 
edges  of  an  inlay  is  what  chiefly  raises  the  question  of  durability  of  this 
class  of  operations.  The  durability  of  porcelain  inlay- work  depends  on 
the  closeness  of  the  meeting  edges  of  inlays  with  those  of  the  enamel  at 
every  point.  The  opaqueness  of  this  cement,  owing  to  the  translucency 
of  the  porcelain,  frequently  very  materially  affects  the  shade  of  a 
cemented  inlay.  The  effect  of  the  cement  on  the  shade  can  be  quite 
accurately  determined  previously  by  first  mixing  a  little  of  the  powder 
of  the  cement  with  water,  placing  it  in  the  cavity,  and  inserting  the 
inlay.     The  shade  of  the  cement  should  accord  well  with  that  of  the 

inlay  or  tooth,  but  be  a  trifle  lighter. 
33 


514  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

Operation  of  Cementation. — Successful  cementation  of  inlays 
largely  depends  on  the  manner  in  which  the  oxyphosphate  is  used,  as 
well  as  on  its  quality.  The  cement  should  be  most  thoroughly  mixed, 
and  its  consistence  should  be  as  nearly  that  of  a  thin  paste  as  possible 
without  too  great  an  impairment  of  its  adhesiveness.  A  cream-like 
consistence,  such  as  is  used  for  gold  cap-crowns,  is  not  reliable.  A 
cement  which  can  be  mixed  moderately  thick  and  still  retain  its  adhe- 
siveness, and  yet  in  that  condition  easily  ooze  out  from  under  and 
around  an  inlay  at  the  edges  under  properly  exerted  pressure,  is  the 
most  suitable.  As  the  action  of  phosphoric  acid  on  the  ordinary  steel 
spatula  affects  the  color  of  the  cement,  an  ivory  or  agate  spatula  is 
the  most  suitable  to  use  for  the  purpose  of  mixing  the  cement. 

Silicate  cement  is  now  to  some  extent  being  used  to  cement  porce- 
lain inlays  as  more  translucent  and  less  soluble  at  the  edges. 

The  inlay  and  cavity  having  been  dried  perfectly,  a  little  of  the 
cement  is  smeared  in  every  part  of  the  cavity  and  on  the  sides  and  bot- 
tom of  the  inlay,  and  especially  in  any  groove  present.  The  cement 
is  then  placed  on  the  inlay  and  the  inlay  inserted  in  the  cavity  and 
gradually  pressed  home.  Before  it  is  quite  in  place,  the  surplus  ce- 
ment should  be  quickly  removed  from  the  surface,  the  inlay  carefully 
examined  to  see  if  it  is  exactly  in  correct  position,  and  the  final  pressure 
given  with  a  properly  shaped  piece  of  wood.  The  final  pressure  should 
be  gentle  and  elastic,  and  exerted  on  the  center  of  the  inlay,  until  all 
surplus  cement  has  oozed  out.  In  approximal  cavities  a  piece  of  tape 
or  floss  silk  may  be  used  to  press  an  inlay  to  place,  but  a  wedge-shaped 
piece  of  wood  is  to  be  preferred.  If  the  rubber-dam  is  used,  leave  it  on 
until  the  cement  has  set.  Varnish  should  be  painted  over  the  inlay. 
In  an  hour  or  at  a  subsequent  sitting,  particles  of  cement  which  may 
still  be  clinging  to  the  tooth  or  inlay  should  be  removed.  If  on  ex- 
amination the  porcelain  should  be  found  to  improperly  project  beyond 
the  surface  of  the  enamel  at  any  point,  it  should  be  reduced  with  finish- 
ing disks  or  strips,  or  Arkansas  stone  points. 


CHAPTER  VII 

SPECIAL  OPERATIONS 

LARGE  CONTOUR  INLAYS — USE  OF  PIECES  OF  PORCELAIN  TEETH — USE  OF 
SiyCCESSIVE  GRADES  OF  BODIES — OCCLUSION  IN  CLOSE  "bITE" — 
PORCELAIN  INLAYS  IN  COMBINATION  WITH  GOLD  OR  AMALGAM 
FILLINGS — ATROPHY    AND    EROSION — PORCELAIN    TIPS — PORCELAIN 

SHOULDERS    PREFERABLE    TO    PINS    FOR   RETENTION — WIRE    LOOP 

SMALL  FRACTURES — ROD  INLAYS — PREPARATION  OF  THE  CAVITY — 
THE  ROD  INLAY — CEMENTATION  AND  FINISHING — POINTS  TO  BEAR 
IN  MIND — TO  FACILITATE  MATRIX  ADAPTATION — TRAY  TO  BAKE 
ON — TO  OVERCOME  CONTRACTION  OF  BODY — TO  AID  REMOVAL 
AND  REMEDY  TEAR  OF  MATRIX — ADVANTAGES  OF  THE  USE  OF  A 
FOUNDATION  BODY  IN  CONTOUR  OPERATIONS — THE  USE  OF  A  LENS — 
POROSITY  OF  PORCELAIN — EDGES  OF  INLAYS — SMALL  INLAYS — 
EFFECT  OF  CEMENT  ON  SHADE — REQUIREMENTS  IN  INLAY-WORK — 
CONSERVATIVE  LIMITATIONS  OF  PORCELAIN  INLAY- WORK 

Large  Contour  Inlays. — When  considerable  contour  is  given  or  a 
corner  is  built  out,  for  instance,  in  a  case  such  as  is  represented  in  Fig. 
1058  and  others  of  that  character,  the  porcelain  should 
always  be  set  at  a  right  angle  to  the  biting  or  incising 
edge  of  the  tooth  under  treatment,  as  shown  at  A,  or 
chipping  is  liable  to  occur.  In  this  and  all  such  cases 
a  projecting  horn  of  the  porcelain  (B)  will  make  a  much 
stronger  anchorage  than  a  platinum  pin.  A  platinum 
pin  in  a  small  mass  of  porcelain  has  a  tendency  to 
weaken  it  by  breaking  up  the  continuity  of  its  structure. 

Use  of  Pieces  of  Porcelain  Teeth. — In  building  up  corners  of  large 
contours  a  piece  of  a  porcelain  tooth  of  the  exact  shade  can  be  placed 
in  the  matrix,  and  the  body  built  around  and  over  it.  The  applied  piece 
of  fused  porcelain  by  its  presence  lessens  the  usual  proportion  of  shrink- 
age of  the  inlay  in  baking  and  simplifies  the  construction  of  a  sharp  cor- 
ner. In  the  use  of  the  high-fusing  porcelain,  after  it  has  been  baked  in 
position  in  the  matrix,  the  work  may  be  adjusted  in  the  tooth,  its  posi- 
tion examined,  and,  should  any  point  of  the  piece  of  porcelain  project 
excessively,  it  can  be  trimmed  off  with  a  carborundum  wheel.  The 
porcelain  should  then  be  washed  and  cleaned  of  the  debris  resulting 
from  the  grinding. 

.  515 


5i6 


CROWN',  BRIDGE-,  AND  PORCELAIN-WORK 


Use  of  Successive  Grades  of  Bodies. — The  use  of  successive  grades 
of  high-fusing  porcelain,  commencing  with  a  very  high-fusing  founda- 
tion, and  followed  by  lower  and  still  lower-fusing  bodies,  often  simpli- 
fies the  operation  of  building  out  a  difficult  corner.  In  such  a  case 
each  application  should  be  biscuited  and  fused  before  the  next  lower- 
fusing  grade  is  added. 

Occlusion  in  Close  Bite. — When  a  large  corner  is  built  on  an  upper 
incisor,  if  the  bite  is  close,  the  porcelain  should  be  depressed  at  the 
point  of  occlusion  with  the  lower  teeth,  and  enough  of  the  incisal  edge 
of  the  lower  antagonizing  tooth  should  be  ground  off  to  leave  a  slight 
space — say  that  of  thin  cardboard — between. 

Porcelain  Inlays  in  Combination  with  Gold  or  Amalgam  Fillings. 
— In-  a  case  of  combined  approximal  and  cervical  decay,  where 
the  shape  is  unfavorable  to  the  formation  of  an  entire  porcelain 
inlay,  or  undesirable,  fill  the  approximal  cavity  with  cohesive  gold, 
extending  it  into  the  cervical  cavity,  trim  the  edge  of  the  gold,  and  then 
form  and  insert  the  inlay  partly  in  the  latter,  as  illustrated  in  Fig.  1059. 


Fig.  1059. 


Fig.   1060. 


Large  amalgam  fillings,  especially  in  either  the  bicuspids  or  molars, 
may  be  treated  in  a  similar  manner.^ 

Atrophy  and  Erosion.^ — In  atrophy  of  the  enamel,  as  illustrated  in 
Fig.  1060,  porcelain  inlay- work  is  specially  suitable.  In  cases  of  erosion, 
where  shrinkage  of  the  gum  causes  exposure  of  a  portion  of  the  root, 
as  shown  in  Fig.  1061,  the  section  of  the  inlay  over  the  root  can  be 
enameled  with  gum-colored  porcelain.  Gum  enamel  fuses  at  a  lower 
heat  than  the  porcelain  it  accompanies,  and  is  to  be  apphed  after  the 
final  baking  of  the  inlay,  but  before  removal  from  the  matrix. 

Porcelain  Tips. — From  an  esthetic  standpoint  porcelain  is  the  most 
suitable  material  to  use  in  the  repair  of  fractured  front  teeth  or  in 
cases  of  atrophy.  The  construction  of  the  porcelain  tips  for  such  cases 
is  one  of  the  most  difficult  operations  to  perform  acceptably  and 
reliably. 

The  application  of  porcelain  tips  is  limited.     Small  pieces  of  porce- 

1  The  silicate  cements  are  now  largely  used  for  this  purpose. 


SPECIAL  OPERATIONS 


517 


lain  will  not  withstand  the  force  of  mastication,  as  in  cases  of  mechan- 
ical abrasion  and  in  some  forms  of  fractures  reliable  anchorage  in  teeth 
with  vital  pulps  is  either  difficult  or  impossible  to  obtain. 

Fig.  1062  illustrates  a  case  of  atrophy  in  which  the  tips  of  the  cen- 
tral incisors  were  contoured  with  porcelain.  The  right  central  shows 
the  porcelain  in  position,  the  left  the  porcelain  tip  ready  to  be  adjusted. 
A  dovetailed  cavity  was  first  formed  in  the  central  portion  of  the  sec- 


FiG.   1061. 

tion  to  be  tipped  or  contoured.  A  piece  of  platinum  foil  was  adapted 
to  the  cavity,  and  high-fusing  porcelain  body  baked  thereon  as  already 
described.  The  platinum  foil  was  then  removed  and  the  tip  cemented 
in  position. 

To  form  an  extremely  strong  porcelain  tip,  select  a  porcelain  tooth 
of  the  correct  shade,  pulverize  finely  the  portion  corresponding  to 
the  part  to  be  restored,  and  use  the  powder  as  the  body  to  form  the 


Fig.   1062. 


Fig.   1063. 


tip.  A  very  high  heat  is  required  to  fuse  the  porcelain  of  artificial 
teeth,  but  the  greatest  possible  strength  in  a  porcelain  tip  is  secured 
by  the  use  of  such  a  body. 

Porcelain  Shoulders  Preferable  to  Pins  for  Retention.^ — For  the 
retention  of  a  porcelain  tip,  a  shoulder  of  the  porcelain,  such  as  is 
illustrated  in  Fig.  1062  is  preferable  to  forming  the  tip  with  a  loop  of 
wire  or  with  platinum  pins,  which  are  to  be  cemented  in  holes  drilled 


5i8  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

in  the  tooth-substance.  The  presence  of  pins,  as  before  mentioned  in 
regard  to  other  operations,  weakens  so  small  a  piece  of  porcelain  by- 
breaking  up  the  continuity  of  its  structure.  The  pins  do  not  form  for 
it  as  secure  or  strong  an  attachment  as  a  porcelain  anchorage  of  mod- 
erate size. 

Wire  Loop. — In  cases  of  fracture  in  which  porcelain  tips  are  required, 
and  the  existing  conditions  do  not  permit  of  the  removal  of  sufficient 
tooth-structure  to  form  a  porcelain  anchorage,  the  use  of  pins  must  be 
resorted  to.  In  such  a  case,  after  the  holes  have  been  formed, — there 
should  not  be  more  than  two, — and  the  parts  properly  prepared,  the 
surface  of  the  fractured  part  is  capped  with  platinum  foil  punctured 
over  the  holes  and  the  pins  inserted.  The  wire  to  form  the  pins  should 
be  of  about  gage  No.  21.  It  should  be  first  rolled  under  a  fine  flat  file 
to  sHghtly  roughen  its  surface.  The  pins  should  extend  from  the  foil, 
or  the  wire  forming  them  be  shaped  in  a  loop,  as  shown  in  Fig.  1063. 
While  the  platinum  cap  and  pins  are  in  position  on  the  tooth,  a  small 
quantity  of  a  very  high-fusing  porcelain  or  foundation  body  is  applied 
to  the  center  of,  the  cap  and  closely  around  the  pins.  The  excess  of 
moisture-  is  absorbed  with  blotting-paper  and  the  surplus  body  re- 
moved with  a  small  brush  from  around  the  margins  of  the  cap.  The 
wire  or  loop  is  then  seized  and  the  whole  gently  removed  from  the 
mouth  and  given  a  biscuit  bake.  On  removal  it  is  readjusted  on  the 
tooth.  The  shrinkage  of  the  foundation  body  is  compensated  for  by 
the  addition  of  more  body,  and  it  is  again  inserted  in  the  furnace  and 
then  given  a  bake  at  the  fusing-heat  of  the  porcelain.  If  the  extension 
of  the  loop  of  wire  above  and  across  the  surface  of  the  cap  occupies 
more  space  than  the  size  and  form  of  the  part  to  be  restored  will  allow, 
the  loop  should  be  bent  down  a  little  against  the  surface  of  the  cap  or 
be  partly  or  entirely  removed  by  grinding,  leaving  only  the  pins. 
Should  the  latter  course  be  necessary,  the  pins  will  then  be  held  in 
position  by  the  foundation  body  which  has  been  fused  around  them. 
The  cap  is  next  placed  on  the  tooth  and  the  margins  of  the  platinum 
burnished  closely  around  that  of  the  fracture  and  the  formation  of  the 
tip  completed  with  porcelain  body  which  fuses  at  a  lower  heat  than  that 
already  used.  After  the  final  fusing  of  the  porcelain  the  foil  is  torn 
from  the  base.  It  will  not  adhere  to  the  pins,  not  having  been  soldered 
to  them.  The  burnishing  of  the  foil  at  the  margins  of  the  cap  after 
the  first  baking  sHghtly  reduces  its  gage  in  comparison  with  the  central 
portion  and  tends  to  effect  a  closer  fit  for  the  porcelain  at  that  part. 
Another  method  is  to  first  cement  the  ends  of  the  wire  loop  into  the 
holes  in  the  dentin,  and  form  the  tip  with  a  cavity  for  the  loop  to  fit 
and  to  be  cemented  into. 


SPECIAL  OPERATIOXS  519 

Small  Fractures. — Fractures  of  the  incisal  edges  of  the  incisors,  of 
the  character  and  as  small  as  those  illustrated  in  Fig.  1064,  cannot  be 
restored  with  porcelain.  The  fractured  part  usually  consists  entirely 
of  enamel,  and  the  area  to  be  operated  on  is  so  small  that  a  reliable 
anchorage  in  the  porcelain  is  not  obtainable.  If  the  form  and  length 
of  the  teeth  will  permit,  the  defect  is  best  remedied  by  trimming  the 
incisal  edge  of  the  adjoining  teeth  and  the  fractured  tooth  to  corres- 
pond in  length,  then  smooth  and  polish. 

When  an  imperfection  of  the  enamel,  decay,  or  a  fracture  involves 
only  the  central  section  of  a  moderately  thick  incisal  edge  of  an  incisor 
or  cuspid,  that  part  may  be  inlaid  with  porcelain  by  shaping  the  cavity 
as  illustrated  in  Fig.  1065. 

In  cases  where  the  fracture  or  imperfection  involves  a  loss  of  nearly 
one-half  of  the  natural  crown,  an  artificial  crown  is  preferable. 


Fig.  1064.  Fig.   1065. 

Rod  Inlays 

The  use  of  rod  inlays  on  the  labial  surfaces  of  the  upper  incisor  teeth 
is  especially  adapted  to  inlays  too  small  to  be  formed  by  fusing  porce- 
lain in  a  foil  matrix  of  the  cavity,  or  in  circular  cavities  or  in  those 
which  can  be  shaped  round. 

Preparation  of  the  Cavity. — The  cavity  to  be  inlaid  is  shaped  with  a 
fine-cut  wheel-bur  of  the  style  shown  in  Fig.  1066,  perfectly  round,  with 
straight  walls,  over  one-thirty-second  and  approximating  one-sixteenth 
of  an  inch  in  depth.  As  an  inlay  of  this  style  cannot  very  well  be 
manipulated  of  a  diameter  less  than  No.  20  gage,  the  cavity  requires 
to  be  enlarged  to  at  least  that  size. 

The  Rod  Inlay. — The  inlay  is  made  from  a  portion  of  one  of  the 
porcelain  rods  (Fig.  1067)  or  circular  pieces  of  porcelain  (Fig.  1068) 
manufactured  for  the  purpose.  The  porcelain  is  mounted  with  shellac 
on  either  end  of  one  of  the  mandrels  as  shown  in  Fig.  1069,  and  gradu- 
ally ground  down  in  the  handpiece  of  the  dental  engine  to  fit  the  cavity, 
using  a  flat  piece  of  carborundum,  and  fine  sand  or  emery  paper  in  the 
final  reduction.  A  micrometer  gage  is  an  aid  in  measuring  the  size 
of  the  bur  to  be  used  and  the  diameter  of  the  inlay  during  the  reduction 
and  fitting. 


520 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Cementation  and  Finishing. — The  inlay  when  fitted  is  detached 
from  the  mandrel,  the  cavity  very  slightly  undercut,  and  the  inlay, 
without  being  ground  or  notched,  cemented  with  oxyphosphate, 
which  will  adhere  tenaciously  to  the  surface  of  the  ground  porcelain. 


Pig.  1066. 


Fig.  1067. 


When  the  cement  has  set  perfectly,  the  porcelain  which  protrudes  above 
the  surface  of  the  enamel  is  ground  level  with  small  carborundum  points 
or  wheels  and  finished  with  Arkansas  stone  points.  Figs.  1070  and 
107 1  show  inlays  that  are  best  inserted  by  this 
method  where  imperfections  or  cavities  exist. 


e  ©QQ 


Fig.   1068. 


Fig.   1069. 

Points  to  Bear  in  Mind 


To  Facilitate  Matrix  Adaptation. — In  the  adaptation  of  a  matrix  in 
an  approximal  cavity  the  process  is  greatly  simplified  by  the  presence 
of  abundant  space  and  freedom  from  interference  by  th  egum-septa. 
In  cases  where  cervical  decay  extends  under  the  gum-margin,  the  cavity 
should  be  previously  packed  with  cotton  or  gutta-percha,  and  the  gum 
pressed  from  normal  position  sufficiently  to  fully  expose  the  edge  of  the 
cavity  and  permit  perfect  adaptation  of  the  matrix  or  taking  an  im- 
pression. In  the  direct  method  packing  the  cavity  of  the  matrix  with 
wax,  in  such  a  case,  is  to  be  recommended,  especially  if  3^^00  0  platinum 
or  gold  foil  is  used,  as  the  wax  will  maintain  the  position  of  the  foil  should 
any  point  press  against  the  gum. 


SPECIAL  CPERATIONS  521 

Tray  to  Bake  on. — The  use  of  fire-clay  trays  is  recommended  in 
preference  to  the  metalhc  for  the  reason,  in  the  opinion  of  the  author, 
that  a  short  circuit  is  frequently  formed  in  a  muffle  in  moving  a  metal- 
lic tray  over  its  surface  by  touching  some  slightly  exposed  part  of  a 
wire. 

To  Overcome  Contraction  of  Body. — In  the  use  of  any  grade  of 
porcelain  body  the  most  extensive  shrinkage  occurs  in  the  first  baking. 
The  body  contracts  from  the  sides  toward  the  center.  To  cause  the 
contraction  to  take  place  from  the  center  toward  the  sides  it  has  been 
suggested  to  place  the  body  in  a  ring  around  the  sides  of  the  matrix; 
this,  however,  is  seldom  practical.  Instead,  a  little  of  the  body  may 
be  removed  from  the  center  of  the  filled  matrix.  When  an  inlay  is 
large  enough  to  permit  it,  the  effect  of  shrinkage  is  controlled  to  a 
considerable  extent  by  serrating  the  body,  thus  dividing  it  into  several 
small  sections. 

To  Aid  Removal,  and  Remedy  Tear  of  Matrix. — The  removal  of  a 
matrix  from  a  cavity  is  often  facilitated  and  the  presence  of  a  large 
tear  in  the  bottom  overcome  by  filling  the  matrix  with  the  porcelain 
body,  on  the  same  principle  that  wax  is  often  applied,  before  removing 
it  from  the  cavity.  The  body  is  placed  in  the  cavity  and  compressed 
with  a  strip  of  tape  or  pellet  of  cotton  to  condense  it  and  absorb  the 
moisture.  The  surplus  is  then  brushed  off  with  a  camel's-hair  brush, 
and  the  matrix  removed  and  baked.  In  the  use  of  high-fusing  porce- 
lain in  such  cases  a  foundation  body  had  best  be  applied,  especially 
when  the  matrix  is  torn. 

Advantages  of  the  Use  of  a  Foundation  Body  in  Contour  Operations. 
— In  contour  operations  it  is  advisable  to  use  a  foundation  or  basal 
body  in  the  first  baking,  as  it  fuses  at  a  higher  heat  than  the  body  used 
to  construct  the  remaining  portion.  The  use  of  a  basal  body  is  advis- 
able, especially  in  a  case  where  the  bottom  of  the  platinum  matrix  is 
cracked  or  broken.  In  the  first  baking  it  covers  over  the  breaks  and 
remains  intact  during  the  application  of  the  remainder  of  the  lower- 
fusing  porcelain  which  is  applied  to  shape  or  build  up  the  inlay,  and 
gives  form  and  rigidity  to  the  base.  As  a  basal  body  fuses  at  a  higher 
heat  than  that  subsequently  applied,  it  should  be  both  ''biscuited"  and 
thoroughly  fused  before  the  application  of  the  additional  lower-fusing 
body. 

The  Use  of  a  Lens. — The  use  of  a  3-inch  lens  magnifying  about  two 
diameters,  mounted  on  a  stand  so  that  the  work  can  be  held  under  it 
and  viewed  at  pleasure,  will  prove  of  great  assistance,  especially  in  the 
manipulation  of  the  porcelain  body  in  the  matrix. 

Small  camel's-hair  artist's  brushes  will  be  found  very  serviceable 


522  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

for  brushing  and  removing  particles  of  the  porcelain  body  around  the 
edge  of  the  matrix,  and  at  times  adjusting  small  portions  of  it  in  proper 
position. 

Porosity  of  Porcelain. — Porosity  of  porcelain  is  attributable  to 
imperfect  packing,  gassing,  heating  too  quickly,  or  overheating. 
Brittleness  will  result  from  the  same  causes  and  from  cooling  too  rapidly. 
The  Indirect  Method  permits  the  entire  operation  to  be  performed  in 
the  laboratory  and  any  failures  are  corrected  without  any  delay  to, 
and  without  the  knowledge  of  the  patient. 

Edges  of  Inlays. — In  all  inlays  it  is  preferable  to  have  the  edges  a 
little  too  low  rather  than  too  high.  If  the  porcelain  is  too  high  it  can 
be  ground  down  and  still  give  good  results,  but  the  original  gloss  is  to 
be  preferred. 

Small  Inlays. — Good  edges  are  difficult  to  obtain  in  porcelain  inlays 
smaller  than  a  pin-head  when  made  in  a  matrix.  In  such  cases  the  use 
of  the  porcelain  rod  method  is  preferable. 

Effect  of  Cement  on  Shade. — In  small  labial  inlays,  unless  the 
cavities  are  deep,  the  cement  will  show  through  the  porcelain  in  such 
wise  as  to  mar  the  intended  effect. 

Requirements  in  Inlay-Work. — An  inlay  should  fit  the  cavity 
so  that  the  edges  shall  be  absolutely  exact  and  not  perceptible.  It 
should  not  rock  or  move  when  inserted  in  position,  and  the  occlusion 
should  be  correct.  Slight  rocking  of  an  inlay  when  the  fusing  is  com- 
pleted and  it  is  fitted  in  the  cavity  is  often  occasioned  by  a  rent  which 
existed  in  the  bottom  of  the  matrix,  causing  an  unevenness  at  that  part. 
This  may  be  effectually  corrected  by  trimming  the  part. 

Conservative  Limitations  of  Porcelain  Inlay-Work.^ — Porcelain 
inlays,  in  the  opinion  of  the  author,  should  be  limited  to  that  class  of 
operations  where  the  question  of  the  exposure  of  a  metallic  filling  to  be 
avoided  is  viewed  from  an  esthetic  rather  than  from  a  practical  stand- 
point. The  advantages  and  durability  of  gold  and  amalgam  fillings 
as  tooth-savers  have  been  too  long  and  too  well  established  to  properly 
permit  of  their  supersedure  by  a  cemented  inlay  formed  of  an  unyield- 
ing material  Hke  porcelain,  except  where  the  question  of  esthetics  is  a 
factor.  If  around  the  entire  circumference  of  a  porcelain  inlay  when 
cemented  in  the  cavity  there  exists  a  single  point  where  the  adaptation 
is  imperfect,  that  point  is  vulnerable  with  even  the  best  cements  so  far 
offered  to  the  profession.  A  corresponding  imperfection  in  a  gold 
inlay,  if  formed  according  to  most  recent  methods,  may  be  remedied 
by  the  burnishing  given  its  feather  edge  against  the  margins  of  the  cavity 
before  and  after  cementation  in  the  final  finishing  of  the  inlay. 


CHAPTER  VIII 
PORCELAIN  AND  PLATINUM  CROWN-WORK 

STRUCTURAL  REQUIREMENTS — PLATINUM  SOLDER — NATURE  OF  ADHESION 
OF  PORCELAIN  FUSED  ON  PLATINUM — APPLICATION  OF  PORCELAIN 
BODY  IN  CROWN-WORK — ^BAKING — DEGREES  OF  HEAT — PORCELAIN 
AND  PLATINUM  COLLAR  OR  PARTIAL  COLLAR  CROWNS — PROCESS  OF 
CONSTRUCTION  OF  COLLAR  CROWN — PARTIAL  COLLAR-CAP — ^BICUSPIDS 
AND  MOLARS — PRACTICAL  METHOD  TO  FORM  OCCLUDING  SECTION — 
CROWN  WITHOUT  A  COLLAR — LIMITATIONS — JACKET  CROWN — 
INCISORS  AND  CUSPIDS  WITH  PLATINUM  JACKET — APPLICATION  OF 
PORCELAIN  VENEER — PROTECTION  OF  THE  INCISAL  EDGE — PORCE- 
LAIN AND  PLATINUM  BICUSPID  CAP-CROWN  WITH  PORCELAIN 
OCCLUSAL  SURFACE — PORCELAIN  AND  PLATINUM  TL^E  CROWN — 
A  PORCELAIN  AND  PLATINUM  BICUSPID  CROWN  WITH  METAL  SUR- 
FACE— APPLICATION  TO  CASES  OF  FRACTURED  PORCELAIN  CROWNS — 
READY-MADE  CROWNS  ON  CAPPED  ROOTS — THE  S.  S.  WHITE,  DAVIS, 
ASH  OR  JUSTI  CROWN  ON  A  CAPPED  ROOT — ALL -PORCELAIN  JACKET 
CROWN- — APPLICATION  OF  VENEER  AND  PORCELAIN  TO  CONE — TO 
FORM  A  VENEER — FORMATION  OF  PORCELAIN  CROWN  WITHOUT  A 
VENEER — REMOVAL  OF  MATRIX  OR  CONE — CEMENTATION — THE 
OVERLAP  CROWN — CROWNING  OF  ROOTS  DECAYED  APART  AT  THE 
BIFURCATIONS-COMMENTS  ON  GRADES  OF  PORCELAIN — COMPOUND- 
ING ARTIFICIAL  TOOTH  BODY 

Structural  Requirements. — In  porcelain  and  platinum  work,  the 
metallic  structure  constitutes  the  foundation  and  the  porcelain  the  part 
to  be  restored.  The  metallic  part  consequently  should  be  made  strong 
and  rigid  and  of  a  character  that  will  furnish  the  best  possible  support 
and  attachment  for  the  porcelain.  The  line  of  union  or  joints  of  the 
sections  composing  the  metallic  part  should  be  closely  fitted  so  as  to 
insure  perfect  contact.  Pure  gold  is  used  ordinarily  as  a  solder  to  unite 
the  parts.  Gold  alloyed  with  the  baser  metals  is  unsuitable,  as  their 
presence  would  stain  the  porcelain.  Only  the  smallest  possible  quan- 
tity of  the  gold  that  will  effect  the  object  should  be  used,  as  subse- 
quently in  the  baking  of  the  porcelain  it  is  entirely  absorbed  by  the 
platinum.  Small  spaces  are  thus  liable  to  be  created  under  the  porce- 
lain at  points  which  tend  to  weaken  the  structure  of  the  crown.     In 

523 


524  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

the  absorption  of  the  gold,  the  sections  of  the  metal  which  touch  where 
it  was  applied  become  sweated  together  in  such  manner  that  they  will 
not  be  separated  by  any  degree  of  heat  subsequently  applied.  This 
absorption  of  the  gold  solder  consequently  may,  in  a  measure,  be 
effected  at  the  time  of  soldering  by  applying  sufficient  heat.  This  is 
allowable  in  soldering  invested  sections  of  the  metal  alone,  but  when 
porcelain  is  included  the  intense  heat  is  liable  to  cause  etching  of  the 
porcelain  from  its  contact  with  the  investing  materials.  Etching  may, 
in  a  measure,  be  avoided  by  varnishing  the  surface  of  the  teeth  with 
shellac  previous  to  investment. 

Platinum  Solder.— Platinum  solder,  25  per  cent,  platinum  to  75 
per  cent,  gold  (see  Part  I,  Chapter  II),  is  recommended  in  preference 
to  pure  gold,  as  it  is  not  absorbed  in  the  baking  of  the  porcelain,  and 
strengthens  as  well  as  unites  the  parts.  The  compound  oxyhydrogen 
blowpipe  flame  is  required  to  fuse  platinum  solder,  the  use  of  which  is 
described  in  Part  I,  Chapter  VI. 

Nature  of  Adhesion  of  Porcelain  Fused  on  Platinum. — Porcelain 
body  fused  on  platinum  adheres  to  the  surface,  but  the  adhesion  is 
only  mechanical.  Consequently,  should  any  change  occur  in  the  form 
of  the  metallic  base,  the  porcelain  is  liable  to  become  detached.  This 
fact  should  be  kept  in  mind  regarding  this  class  of  operations.  The 
surface  of  the  metal  that  is  to  receive  the  porcelain  should  be  rough- 
ened or  serrated  with  a  sharp-pointed  instrument,  at  parts  that  sug- 
gest it,  and  where  it  is  permissible,  either  indented  or  punctured. 

Submitting  the  surface  of  the  platinum  to  the  action  of  aqua-regia, 
also  sprinkling  coarse  platinum  filings  on  the  surface  of  a  section  of 
the  metal  and  attaching  them  with  an  atom  of  pure  gold,  furnishes  a 
means  of  secure  adhesion  for  porcelain  body.  By  simply  scratching 
the  surface  of  the  platinum  quite  a  reliable  attachment  of  the  porcelain 
to  the  metal  is  obtained,  as  is  demonstrated  in  the  construction  of  arti- 
ficial plates  of  porcelain  on  platinum — the  form  termed  continuous-gum 
work. 

Application  of  Porcelain  Body  in  Crown-Work. — The  metallic 
structural  framework  of  the  crown  should  be  thoroughly  cleansed  of 
borax  with  acid  and  washed  free  of  all  particles  of  foreign  matter.  Any 
sharp  edges  or  points  that  are  Hable  to  be  exposed  in  the  finished  crown 
are  to  be  rounded  and  smoothed.  The  method  of  selecting  shades  and 
applying  porcelain  body  in  crown-work  is  similar  in  principle  to  that 
explained  respecting  high-fusing  body  used  in  inlay- work.  The  porce- 
lain body  should  be  placed  on  a  clean  glass  or  porcelain  slab  and  mixed 
with  pure  water  to  a  dough-hke  consistence.  The  addition  of  a  small 
quantity  of  dissolved  gum  tragacanth  is  to  agglutinate  the  particles 


PORCELAIN  AND  PLATINUM  CROWN-WORK 


525 


of  the  body  in  difficult  contour-work.^  The  crown  is  held  by  the  post 
in  a  pin- vise,  as  shown  in  Fig.  1072,  during  the  application  of  the  body. 
By  tapping  the  handle  of  the  vise  with  the  mixing  spatula  as  the  body 
is  applied  it  is  packed  into  the  interstices  of  the  work  and  the  moisture 
is  brought  to  the  surface,  to  be  absorbed  with  blotting  or  bibulous  paper. 


Fig.   1072. 

More  body  is  then  gradually  added  until  it  assumes  the  general  form  and 
proportions  desired  in  the  finished  crown.  As  the  proportion  of  shrink- 
age that  takes  place  in  the  first  bake  approximates  one-third  the  bulk, 
calculations  should  be  made  accordingly.  The  work  is  then  ready  to 
receive  the  first  fusing. 

Baking. — The  baking  of  porcelain  body  in  crown- work  is  conducted 
similar  to  that  described  for  porcelain  inlays  in  Chapter  VI.  The  first 
bake  should  be  the  "biscuit  bake,"  effected  with  a  heat  which  will 

'  Dr.  F.  T.  Van  Woert's  formula  is: 

Gum  Tragacanth 3"^  oz. 

Alcohol 3-^  oz. 

Water K  oz. 

Dissolve  the  gum  in  the  alcohol  and  then  add  the  water,  stirring  rapidly. 


526  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

cause  the  body  to  shrink  and  become  hard  but  not  glazed,  though  the 
mass  is  covered  with  shining  particles.  If  the  work  is  allowed  to  remain 
in  the  furnace  for  the  first  baking  until  the  fusing-point  is  reached, 
porosity  and  imperfections  are  liable  to  appear  in  the  final  application 
and  fusing.  After  the  crown  has  received  the  biscuit  bake  it  may  be 
adjusted  in  the  mouth  or  on  the  articulating  model  and  the  porcelain 
ground  off  or  added  to  where  necessary  for  proper  occlusion  and  ap- 
proximal  contact. 

For  the  second  bake  the  seams  and  crevices  are  filled  and  the  body 
added  until  the  parts  are  slightly  larger  than  is  required.  As  in  the 
previous  application  of  body,  all  the  moisture  possible  should  be  brought 
to  the  surface  and  absorbed.  The  less  moisture  allowed  to  remain 
and  the  greater  the  condensation  of  the  particles  each  time,  the  less 

the  shrinkage  which  will  take  place. 
^^^Oi  For  the  third  or  final  fusing,  after 

//^iSil^i        M^fWiiW^'%\  necessary    addition    of    body    is 

li!^teM«r       MWiml'h'^mS  made,  the  crown  is  slowly  heated  in 
^-Muii^]^!^^;^^       the    furnace    and    allowed    to    remain 
Fig.  1073.  until  the  surface  of  the  body  assumes 

a     smooth,     glazed     appearance     cor- 
responding to  that  of  natural  enamel. 

After  the  final  baking,  the  crown  should  be  allowed  to  cool  very 
slowly  to  temper  the  porcelain.  Too  rapid  cooling  will  injure  the 
crown- work,  if  not  destroy  it.  If  an  electric  furnace  is  used,  the  cur- 
rent can  be  turned  off  and  the  work  allowed  to  remain  until  cool;  or  it 
can  be  removed  and  placed  in  a  muffle  provided  for  cooling  purposes. 
When  cool,  the  crown  should  be  dipped  in  water  before  handling. 
Fig.  1073  illustrates  forms  of  fire-clay  supports  on  which  a  crown 
can  be  placed  during  the  fusing  of  the  porcelain. 

Degrees  of  Heat. — In  crown-work  the  heat  as  registered  by  the 
pyrometer  for  the  first  bake  should  be  200°  below  the  fusing-point  of 
the  porcelain  body  used;  that  of  the  second,  or  other  primaty bakes, 
150°,  and  of  the  final  bake  the  fusing-point,  at  which  degree  the  crown 
should  be  kept  for  twenty  seconds. 

Porcelain  and  Platinum  Collar  or  Partial  Collar  Crowns 

Process  of  Construction  of  Collar  Crown. — The  collar  should  be 
made  of  platinum,  about  gage  No.  29  to  30,  or  iridio-platinum,  gage  31  to 
32,  and  the  piece  which  caps  the  collar  of  about  platinum  plate  No,  32. 
The  collar  or  partial  collar-cap  is  first  constructed  and  fitted  to  the  end  of 
the  root  as  illustrated  in  Fig.  1074,  according  to  one  of  the  methods  de- 


PORCELAIN  AND  PLATINUM  CROWN-WORK  527 

scribed  at  page  211.  The  post  should  be  substantial,  and  in  all  cases 
be  extended  some  distance  above  the  surface  of  the  cap  as  an  attach- 
ment for  the  porcelain.  It  should  be  closely  fitted  to  the  cap  at  the 
orifice  of  the  canal  by  perforating  the  platinum  and  forcing  it  to  position, 
and  then  united  to  the  cap  with  pure  gold  or,  better,  platinum  solder. 
A  suitable  cross-pin  tooth  is  selected,  and  ground  and  fitted  on  the  cap; 
a  shade  slightly  darker  than  the  corresponding  natural  tooth  is  to  be 
preferred,  as  the  color  is  generally  lightened  in  the  baking.  Usually  in 
the  case  of  incisors  and  cuspids  it  will  be  necessary  to  reduce  the  di- 
mensions of  the  post  to  permit  it  to  pass  between  the  pins,  and  in  many 
cases  also  to  grind  a  groove  in  the  porcelain  facing  for  its  reception. 
This  is  necessary  to  allow  the  tooth  to  assume  the  proper  position  on 
the  cap,  as  the  bases  of  most  porcelain  facings  will  be  found  when  fitted 
to  hang  over  the  space  occupied  by  the  post  in  the  root-canal.  The 
pins  should  be  bent  around  the  post  in  such  manner  as  to 
retain  the  facing  in  position  during  the  application  and 
baking  of  the  porcelain;  or,  the  crown  should  be  invested 
and  the  pins  soldered  to  the  post  with  pure  gold,  which  is 
generally  the  better  method  to  pursue. 

Both  post  end  and  pins  should  entirely  clear  the  occlu- 
sion of  the  antagonizing  teeth. 

The  crown  when  soldered  is  boiled  in  acid  to  remove 
the  flux,  and  having  been  fitted  on  the  model  or  in  the 
mouth  to  determine  the  accuracy  of  the  parts  and  then 
thoroughly  cleansed,  is  ready  for  the  application  of  the 
porcelain  body.  The  body  for  a  crown  of  this  kind 
should  be  nearly  as  high-fusing  as  that  of  the  porcelain  ^^'^-  ^°74. 
facing  so  as  to  afford  the  required  strength. 

In  cases  where  the  porcelain  facing  projects,  as  shown  in  gold  crown- 
work  in  Fig.  314,  the  part  can  be  filled  with  porcelain.  Should  the 
cervico-labial  section  of  a  collar  be  exposed  to  view,  a  little  of  the  porce- 
lain may  be  extended  onto  the  collar  at  that  point  so  as  to  hide  the  metal, 
but  it  should  be  graduated  off  at  the  sides  toward  the  approximal 
spaces. 

Partial  Collar-Cap. — When  a  partial  collar-cap  is  used,  should  the 
cervico-labial  margin  of  the  porcelain  facing  extend  perceptibly  be- 
yond the  line  of  the  edge  of  the  cap,  the  projecting  portion  of  the  porce- 
lain should  be  trimmed  and  re-enameled  in  the  baking. 

Bicuspids  and  Molars. — Bicuspid  and  molar  crowns  can  be  con- 
structed in  a  similar  manner  by  using  a  suitable  facing  on  the  cap, 
and  building  up  the  occluding  surface  and  cusps  with  the  body.  A 
small  additional  post  or  bar,  to  securely  attach  and  support  the  palatal 


528 


CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 


cusps,  may  be  added  and  soldered  to  the  cap,  as  shown  in  the  case  of 
a  bicuspid  in  Figs.  1075,  1076  and  1077. 

Practical  Method  to  Form  Occluding  Section. — The  length  of  the 
palatal  section  of  the  crown  and  form  of  the  cusps  are  quickly  and  ac- 
curately determined  by  placing  the  porcelain  body — preferably  of  the 
first  bake  or  both  first  and  second  bakes,  foundation  body — of  a  dough- 
like consistence,  in  a  mass  in  position  on  the  cap,  packed  against  the 
facing,  inserting  in  the  mouth  or  on  the  model,  occluding  the  teeth  on 


Fig.  1075. 


Fig.   1076. 


Fig.   1077. 


the  body,  and  removing.  The  occluding  teeth  in  leaving  their  impres- 
sion on  the  body,  shape  and  outline  the  form  the  occluding  surface 
of  the  crown  should  be.  The  porcelain  body  is  then  trimmed  and 
properly  shaped  in  accordance  with  the  form  of  a  natural  crown.  Fig. 
1078,  and  then  given  the  biscuit  bake.  Long  cusps  should  be  avoided. 
More  body  is  again  applied,  guided  by  the  occluding  teeth,  to  compen- 
sate for  the  shrinkage,  and  the  usual  bakes  given.  When  a  foundation 
body  is  used,  it  should  be  thoroughly  fused  to  develop  its  greatest 


Fig.   1078. 


Fig.  1079. 


Strength  before  the  application  of  a  lower  fusing  body.  If  the  glazed 
surface  should  cause  the  dry  particles  to  flake  off,  dull  it  with  a  carbo- 
rundum point.  A,  Fig.  1079,  shows  the  appearance  of  the  crown  after 
the  first,  and  B  after  the  final  bake. 

Crown  Without  a  Collar. — A  porcelain  and  platinum  crown  without 
a  collar  is  made  by  fitting  into  the  root  a  substantial  iridio-platinum 
post,  and  capping  the  root  with  a  disk  of  platinum.  A  porcelain  de- 
tached-post crown  is  then  fitted  over  the  end  of  the  post  and  attached 


PORCELAIN  AND  PLATINUM  CROWN-WORK  529 

with  porcelain.  The  disk  of  platinum  should  be  about  gage  No.  32, 
unless  it  is  to  be  removed  after  the  crown  is  baked,  in  which  case  it 
should  be  made  about  gage  No.  40  or  thinner. 

Limitations. — Porcelain  and  platinum  crowns  of  the  forms  above 
described  for  either  the  anterior  or  posterior  teeth  are  not  suitable  for 
a  close  occlusion,  or,  as  ordinarily  termed  a  "close  bite,"  as  fracture  of 
the  porcelain  is  sooner  or  later  quite  certain  to  occur.  Porcelain  and 
gold  construction  in  such  cases  should  be  given  the  preference. 

Platinum  and  Porcelain  Jacket  Crown 

This  crown  consists  of  a  cone-shaped  combined  platinum  and  por- 
celain cap  fitted  like  a  jacket  over  a  natural  tooth,  with  or  without  a 
pulp.  It  presents  good  qualities  of  many  of  the  best  forms  but  not 
the  strength.  It  is  especially  suitable  in  the  crowning  of  pitted  and 
malformed  peg-shaped  teeth  and  cases  of  erosion,  as  it  permits  the 
formation  of  a  crown  without  the  exposure  of  metal  at  the  labial  aspect 
and  in  most  cases  without  removal  of  the  pulp. 

It  requires  the  least  possible  removal  of  tooth-structure 
to  permit  the  mounting  of  the  crown.  Its  natural  appear- 
ance admits  of  the  performance  of  operations  of  a  most 
artistic  character. 

When  the  construction  is  so  conducted  that  the  incisal 

edge  is  protected  with  metal,  it  forms  a  crown  which  for 

1  ,        ,  '         ,  .  ,       , ,  Fig.  1080. 

strength  approaches  that  of  porcelam  and  gold. 

In  pulpless  teeth  a  post  cemented  in  the  root  independent  of  the 
crown  much  simplifies  any  required  reconstruction  of  the  form  of  the 
natural  crown. 

Incisors  and  Cuspids  with  Platinum  Jacket. — The  crowning  of  a 
central  incisor  will  serve  as  a  t3T)ical  case.  Fig.  1080  represents  the 
shape  of  the  prepared  tooth  with  a  vital  pulp.  If  the  crown  is  broken 
off  or  decayed  to  the  gum  margin,  a  post  is  inserted  in  the  root  and 
shaped  with  cast  gold  or  amalgam  to  a  somewhat  conical  form.  A  collar 
of  platinum  (gage  No.  31)  the  full  length  the  crown  is  to  be,  is  made  and 
fitted  to  the  prepared  tooth  or  root.  The  use  of  an  amalgam  die 
made  from  an  impression  taken  in  a  tube  with  impression  compound  wiU 
facilitate  this  part  of  the  operation. 

The  lines  of  the  lingual  and  labial  surfaces  of  the  adjoining  teeth  are 
marked  on  the  platinum.  The  palatal  portion  of  the  collar  is  cut  away 
to  this  line,  so  as  to  clear  the  lower  teeth  in  occlusion  (Fig.  1081).  A 
piece  of  platinum,  of  the  same  gage,  is  soldered  over  the  collar,  to  form 
the  palatal  wall.  The  cap  is  fitted  in  the  mouth,  and  the  labial  section 
34 


530  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

of  the  collar  ground  thin  enough  to  enable  the  platinum  to  be  pressed 
and  burnished  against  the  tooth  or  the  built-up  amalgam.  If  this 
cannot  be  done  satisfactorily,  trim  off  the  platinum  the  same  as  on  the 
palatal  side  and  solder  a  piece  of  platinum  foil  over  the  part  instead. 
It  must  be  remembered  that  in  this  soldering  only  the  least  possible 
quantity  of  pure  gold  should  be  used.  At  this  stage  the  cap  will 
assume  the  form  seen  at  Fig.  1082. 

Application  of  the  Porcelain  Veneer.- — In  this  style  of  crown-work 
teeth  having  living  pulps  afford  so  limited  a  space  for  the  porcelain 
facing  as  not  to  permit  the  use  of  one  with  pins  for  its  re- 
tention on  the  cap  during  the  application  of  the  porcelain 
body.  Facings  can  be  made  of  the  porcelain  body  alone  for 
a  molar  or  second  bicuspid,  but  the  results  respecting 
appearance  would  be  unsatisfactory  for  the  anterior  teeth. 
Veneers  formed  from  artificial  teeth  are  preferably  used  for 
""■  '°'--  this  class  of  work  as  a  rule. 

Pulpless  teeth,  and  in  some  cases  those  with  calcification  of  the  pulp, 
will  stand  the  removal  of  sufficient  of  the  natural  crown  to  allow  of 
the  formation  of  a  cap  which  will  permit  the  use  of  a  facing  with  pins 
that  can  be  soldered  to  it. 

A  thin  veneer  of  porcelain  to  represent  the  tooth  is  made  by  selecting 
an  ordinary  porcelain  tooth  of  the  proper  size  and  shade,  removing  the 
pins  and  grinding  it  down  as  described  in  Part  I,  Chapter  III,  and  illus- 
trated at  A,  Fig.  1082.  The  veneer  is  ground  and  fitted  to  assume  a 
proper  position  on  the  cap.  Porcelain  body  is  then  apphed  and  the 
veneer  pressed  to  place,  surplus  moisture  absorbed,  and 
particles  of  body  removed.  It  is  possible  to  fit  the 
veneer  held  by  the  body  on  the  cap  in  the  mouth  when 
desirable.  The  cap  and  veneer  are  removed  and  placed 
on  silex  on  a  slab,  with  the  face  of  the  veneer  resting 
downward  on  the  silex  to  retain  it  in  position,  and  the 
whole  is  then  placed,  baked,  and  the  body  biscuited.  Fig.  1082. 
Another  method  is  to  gently  remove  the  veneer  from 
the  cap,  disturbing  the  body  as  little  as  possible,  and  insert  the  cap 
without  the  veneer  in  the  furnace.  When  the  cap  is  baked  the 
veneer  will  be  found  to  fit  in  the  indentation  in  the  body.  In  this  way 
the  excessive  shrinkage  of  the  first  baking  and  the  consequent  slight 
displacement  of  the  veneer  are  overcome.  For  the  second  baking  the 
veneer  is  then  placed  on  the  cap  with  the  necessary  body  to  attach  it 
and  slowly  heated  and  baked.  The  body  should  be  placed  over  and  on 
the  incisal  edge  of  the  cap  and  around  on  the  sides  as  far  as  permissible 
to  secure  the  greatest  amount  of  attachment  for  the  porcelain. 


PORCELAIN  AND  PLATINUM  CROWN-WORK  531 

After  both  the  first  and  second  bakes  the  work  should  be  fitted  in 
the  mouth  and  any  of  the  changes  incident  to  shrinkage  of  the  porcelain 
body  noted  and  corrected.  Any  necessary  slight  alteration  respecting 
the  position  or  size  of  the  veneer  and  the  fused  applied  porcelain  body 
should  also  be  made  at  these  stages  of  the  construction  so  that  the 
porcelain  may  be  enameled  in  the  final  bake,  which  should  be  most 
carefully  conducted  in  regard  to  heating  and  cooHng.  After  the  final 
bake  the  exposed  surface  of  the  platinum  should  be  polished.  Crowns 
of  this  style  can  be  well  cemented  only  with  oxyphosphate.  Fig.  1083 
represents  the  finished  crown. 

Protection  of  the  Incisal  Edge. — To  protect  the  incisal  edge  of  a 
crown  of  this  style  the  palatal  side  of  the  collar  is  made  of  iridio-plati- 
num  plate  instead  of  platinum,  of  about  No.  30  gage  or  heavier,  as  the 
character  of  the  occlusion  suggests.  The  end  of  the  strip  is  brought  over 
the  incisal   edge  in  a  manner  to  protect  the  porcelain  in  occlusion,  as 


Fig.  1083.  Fig.   1084.  Fig.   1085. 

shown  at  P  in  Fig.  1084,^  the  same  as  in  porcelain  and  gold  work.  In 
cases  of  jacket-crowns  where  the  space  will  permit,  a  porcelain  facing 
with  pins  may  be  used  and  the  pins  soldered  to  the  cap,  as  shown  in 
Fig.  1085. 

Porcelain  and  Platinum  Bicuspid  Cap-Crown  with  Porcelain  Oc- 
clusal Surface. — When  the  natural  tooth  is  broken  down  and  pulp- 
less,  the  following  method  can  be  practiced:  A  platinum  collar  is  made 
and  fitted,  with  the  labial  section  prepared  and  a  veneer  adjusted  in 
the  same  manner  as  in  the  method  just  explained.  The  edge  of  the 
collar  should  clear  the  occluding  teeth  about  one-thirty-second  of  an 
inch.  (See  Fig.  1086.)  While  the  collar  is  in  position,  a  layer  of 
platinum  foil  is  packed  in,  over,  and  around  the  end  of  the  root  or  any 
part  of  the  natural  tooth  present  (A).  Porcelain  body  is  then  packed 
in  on  the  platinum  foil,  the  space  being  filled  even  with  the  edge  of  the 
collar.  The  veneer  is  placed  in  position  against  the  porcelain  body  and 
the  body  packed  around  it.     The  crown  is  then  carefully  removed  and 

1  Dr.  W.  A.  Capon's  method. 


532 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


baked.  After  baking  it  is  placed  in  the  mouth,  the  occlusion  noted,  the 
cusps  properly  shaped  with  body  by  occluding  the  teeth  on  the  applied 
body,  and  the  final  fusing  of  the  porcelain  performed.  Fig.  1087  illus- 
trates the  completed  bicuspid  crown.  Fig.  1088  shows  a  molar  con- 
structed by  this  method.  The  construction  of  this  crown  may  be 
varied  by  soldering  the  foil,  or  a  very  thin  piece  of  platinum  plate 
placed  inside  the  collar,  to  its  sides,  using  a  porcelain  facing  instead  of  a 
veneer,  and  soldering  the  pins  to  the  foil  or  thin  plate.     The  porcelain 


Fig.   1087. 


Fig.   I 


forming  the  occlusal  section  being  encompassed  by  the  metal,  develops 
great  strength.  It  is  a  form  of  crown  that  admits  of  extensive 
appHcation. 

A  Porcelain  and  Platinum  Bicuspid  Crown  with  Metal  Occlusal 
Surface. — This  form  is  applicable  to  teeth  with  vital  pulps  as  well 
as  pulpless.  The  method  is  as  follows:  The  tooth  or  root  is  prepared 
the  same  as  for  an  all-gold  crown  and  enough  of  the  labial  section  re- 
moved to  allow  for  the  veneer  (Fig.  1089).     If  badly  broken  down 


Fig.   10 


Fig.   1090. 


Fig.   1091. 


it  should  be  built  up  with  a  post  and  amalgam.  A  collar  of  platinum 
is  made  and  fitted  the  same  as  for  an  all-gold  crown,  and  trimmed  free 
of  the  occluding  teeth.  A  suitable  occlusal  surface  is  made  by  stamping 
up  a  piece  of  annealed  iridio-platinum  plate.  No.  30  gage,  or  heavier,  if 
the  case  should  suggest  it  for  strength.  The  palatal  half  is  soldered  to 
the  collar,  but  the  labial  portion  is  left  unsoldered  and  free  (Fig.  1090), 
to  permit  the  front  portion  of  the  collar  to  be  manipulated.  The  labial 
section  of  the  collar  is  next  ground  thin  and  pressed  inward  against  the 


PORCELAIN  AND  PLATINUM  CROWN -WORK  533 

tooth,  to  make  room  for  the  porcelain  veneer.  It  will  then  appear  with 
the  occlusal  surface  as  shown  at  Fig.  1091.  Puncture  the  thin  platinum 
over  the  labial  surface,  and  select  and  fit  a  porcelain  veneer  to  represent 
the  tooth.  Pack  in  porcelain  body  and  fit  the  veneer  in  position  in 
the  mouth.  Carefully  remove  and  bake  in  the  furnace.  Next  refit 
in  the  mouth,  make  any  necessary  changes,  add  more  body,  and  give 
the  final  baking.  The  platinum  is  then  polished,  after  which  the  crown 
is  ready  to  be  cemented.     Fig.  1092  represents  the  finished  crown. 

The  form  of  crown  just  described  can  be  used  in  bicuspids  in  all 
cases,  more  especially  where  there  is  a  close  occlusion.  In 
bridge-work,  a  porcelain-faced  dummy  backed  with  gold  can 
be  soldered  to  this  form  of  crown  to  represent  a  first  bicus- 
pid, the  precaution  being  taken  to  heat  and  cool  the  in- 
vestment slowly.  ■  ^°^^' 

Porcelain  and  Platinum  Tube  Crown. — This  crown  is  for  use  in 
cases  where  the  natural  crown  is  absent  to  the  line  of  the  cervix  and  a 
metallic  collar  is  not  used. 

The  root  is  ground  even  with  the  margin  of  the  gum.     An  iridio- 

platinum  post  is  fitted  and  cemented  in  the  root,  as  seen  in  section  in 

Fig.  1093,  and,  if  an  excessive  enlargement  of  the  root-canal  exists, 

amalgam  is  packed  in  the  orifice  of  the  canal  around  the  post.     In  the 

case  of  a  broken  artificial  crown  where  the  post  remains  with  its  end 

protruding  from  the  root,  the  tube  is  to  be  shaped  to  fit 

over  the  post.     Take  a  piece  of  wire,  of  the  gage  of  the 

post,  and  twist  platinum  foil  around  it  so  that  the  foil  shall 

form  a  tube.     Slip  the  tube  on  the  post  in  the  root.     Cut 

a  disk  of  platinum  foil  fully  the  size  of  the  end  of  the  root, 

puncture  it  in  the  center,  and  slip  it  over  the  tube  on  the 

post.     Draw  off  tube  and  disk  carefully,  and  solder  them 

together  with  the  smallest  possible  quantity  of  pure  gold. 

This   forms  a  combined  tube   and    cap.     Adjust   in    the 

Fig.  1093.  mouth  and  burnish  the  platinum  disk  closely  to  the  root. 

Pack  porcelain  body  in  a  thick  paste  around  the  tube  and 

fit  a  veneer  (as  shown  in  Fig.   1082)  in  proper  position  against  the 

body,  remove,  and  bake. 

If  a  porcelain  facing  having  pins  can  be  fitted  and  used,  the  pins 
may  be  soldered  to  the  tube  with  a  little  pure  gold  to  retain  it  in  correct 
position  before  the  application  of  the  porcelain  body;  if  not,  the  use  of 
a  veneer  may  be  resorted  to,  the  same  as  in  the  preceding  cases.  After 
baking,  place  the  crown  in  position,,  burnish  the  platinum  thoroughly 
at  the  gum  line,  and  trim  off  the  excess.  Add  body  where  required  and 
give  the  final  baking.     It  is  optional  whether  the  platinum  be  allowed 


534  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

to  remain  on  the  base  of  the  crown  or  not,  but  the  portion  at  the  cer- 
vico-labial  section  is  generally  removed  for  the  sake  of  appearance. 
Fig.  1093  shows  the  finished  crown  in  section.  Should  this  crown 
fracture  in  use,  it  can  be  replaced  without  disturbing  the  post  in  the 
root.^ 

Application  to  Cases  of  Fractured  Porcelain  Crowns. — The  method 
just  described  can  be  applied  to  advantage  at  times  in  the  case  of  an 
incisor  or  cuspid  all-porcelain  crown  which  has  been  broken  off,  leav- 
ing its  post  extending  from  the  end  of  the  root. 

Ready-Made  Crowns  on  Capped  Roots. — The  Logan  ready-made 
porcelain  crown  may  be  attached  with  porcelain  to  collar  or  partial 
collar-caps.  The  end  of  the  root  is  first  capped  with  platinum  and  the 
root-canal  prepared  to  receive  the  post  of  the  intended  crown.  At  the 
palatal  section  of  the  crown  a  V-shaped  piece  is  removed  sufficient  to 
fully  expose  the  post  and  base  of  the  crown,  as  shown  in  Fig.  1094.     The 


Fig.   1094.  Fig.   1095.  Fig.   1096. 

cap  and  crown  are  cemented  with  wax,  removed,  invested,  and  cap 
united  to  post  with  a  little  pure  gold.  The  heating  and  cooling  should 
be  done  slowly  to  avoid  fracture  of  the  porcelain.  The  open  slot  per- 
mits the  body  to  be  applied  and  the  shrinkage  that  occurs  in  the  baking 
to  be  filled  in  so  as  to  form  a  solid  connection  of  porcelain  between  cap 
and  crown. 

The  S.  S.  White,  Davis,  Ash  or  Justi  Crown  on  a  Capped  Root.^ — Any 
of  these  crowns  can  be  advantageously  set  on  a  platinum  cap  in  the 
following  manner:  Cap  the  end  of  the  root,  using  platinum  instead  of 
gold  to  form  the  cap,  and  a  round  iridio-platinum  post  instead  of  a 
manufactured  post.  Grind  and  fit  a  Davis  crown  in  proper  position 
on  cap  with  a  V-shaped  space  cut  out  of  each  of  the  sides,  as  shown  in 
Fig.  1095.  These  spaces  are  for  the  purpose  of  permitting  the  porcelain 
body  to  be  properly  placed  and  baked  around  the  post  and  between  the 
cap  and  crown.     When  the  crown  is  fitted  to  the  position  it  is  to  assume 


PORCELAIN  AND  PLATINUM  CROWN-WORK  535 

on  the  cap,  the  porcelain  should  rest  on  or  touch  the  cap  at  a  labial  and 
a  palatal  point  to  steady  it  during  the  first  baking  of  the  body. 

To  attach  the  crown  and  cap  together  for  the  first  baking  place  some 
of  the  body  mixed  thin  in  the  post  hole  of  the  crown,  and  settle  it  to 
place  on  the  post  and  cap  and  absorb  the  moisture  with  bibulous  or 
blotting-paper.  At  this  stage  the  crown  may  be  adjusted  in  the  mouth 
to  positively  assure  its  correct  alignment.  It  is  then  carefully  removed 
and  baked.  The  heat  applied  should  be  sufficient  only  to  biscuit  the 
body.  It  should  then  be  adjusted  in  the  mouth  and  any  necessary 
trimming  or  polishing  done,  the  parts  thoroughly  cleaned,  and  the 
final  applications  of  body  made.     Fig.  1096  shows  the  finished  crown. 

All-Porcelain  Jacket  Crown 

The  crown  is  formed  on  a  cone  of  platinum  foil  that  is  removed  after 
the  porcelain  jacket  or  crown  has  been  baked.  The  tooth  is  trimmed 
and  shaped  to  the  form,  as  shown  in  Figs.  1097  and  1098,  with  a  shoulder 


'di*===4)' 


Fig.    1097.  Fig.   1098. 

or  ledge  at  the  cervix  just  sufficient  to  make  an  even  joint  with  the 
edge  of  the  porcelain  jacket  or  cap.  This  shoulder  is  necessary,  as  it 
gives  to  the  porcelain  an  edge  that  will  not  chip  in  removal  of  the  ma- 
trix. In  the  finished  crown,  if  its  sides  are  made  flush  with  the  root, 
the  result  will  be  a  non-irritating  joint  to  the  tissues.  Form  a  copper 
tube  that  fits  under  the  gum  beyond  the  shoulder;  take  an  impression 
with  compound  in  the  tube,  chill,  remove  and  form  an  amalgam  die. 
Taper  off  the  shank  of  the  die,  take  an  impression  and  "bite"  with  wax, 
fit  the  die  in  the  part  representing  the  tooth  and  run  models.  The 
die  will  then  be  found  in  the  same  position  as  in  the  mouth. 

Remove  the  die  and  with  a  wire  measure  the  circumference  of  the 
tooth  at  the  untrimmed  cervical  section  (Fig.  1099).  Cut  a  piece  of 
Mo  00  platinum  foil  about  three-eighths  of  an  inch  wider  than  the  length 
of  the  trimmed  portion  of  the  tooth  from  the  shoulder  to  the  point  and 
one-sixteenth  of  an  inch  longer  than  the  measure.  Cut  the  corners 
as  shown  at  the  dotted  lines  CC,  Fig.  1 100.     Wrap  the  platinum  around 


536 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


a  cone-shaped  instrument  or  mandrel  with  the  large  end  lapped  about 
one-thirty-second  of  an  inch.  Remove  the  platinum  and  seize  at  the 
seam  at  the  large  open  end  with  a  clamp,  as  illustrated  in  Fig.  iioi, 
and  towards  the  small  end  close  to  the  edge,  unite  the  seam  with  a 
mere  particle  of  pure  gold,  as  indicated  at  G. 

The  cone,  which  is  slightly  larger  than  the  cervix  of  the  tooth,  is  now 
slipped  over  the  die  and  pressed  down  as  far  as  it  will  go  (Fig.  1102), 


Fig.  1099. 


Fig.   1 100. 


Fig.  iioi. 


first  by  finger  pressure  and  then  by  pressure  of  cotton  wrapped  around 
it,  and  the  platinum  is  brought  as  closely  as  possible  to  its  form.  Burn- 
ish the  sides  by  moving  the  burnisher  toward  the  neck,  not  sidewise. 
Close  the  small  end  by  pinching  it  together  and  bending  it  down,  then 
cut  off  the  surplus  (Fig.  1103). 

To  bring  the  platinum  into  the  groove  on  the  die,  use  a  cord  or 
annealed  copper  wire  about  gage  No.  26  and  burnishers,  annealing  fre- 


FlG.  II02. 


Fig.  1103. 


Fig.  1104. 


Fig.  1105. 


quently  (Fig.  1104).  Remove  the  cone  from  the  die,  seize  it  on  the 
side  opposite  to  the  seam  and  direct  the  flame  so  as  to  draw  the  particle 
of  gold  first  applied  along  the  seam  and  entirely  unite  it.  At  the  shoul- 
der trim  the  overhanging  edge  to  one-thirty-second  of  an  inch  surplus 
(Fig.  1 105).  The  cone  may  now  be  adjusted  on  the  tooth  to  determine 
its  accuracy. 

The  porcelain  section  is  formed  either  by  the  use  of  a  porcelain  veneer 
and  body  or  with  porcelain  body  alone. 

Application  of  Veneer  and  Porcelain  to  Cone 

To  Form  a  Veneer. — Select  a  vulcanite  tooth  or  a  detached-post 
crown  a  shade  darker  than  will  be  required,  as  the  heat  will  lighten  it. 


PORCELAIN  AND  PLATINUM  CROWN-WORK  537 

If  a  tooth,  remove  the  pins  and  with  carborundum  wheels  and  cones 
grind  it  until  only  a  thin  veneer  is  left  (Fig.  11 06),  which  will  fit  in 
correct  position  over  the  cone,  as  shown  in  Fig.  1107.  If  the  outer 
surface  of  the  veneer  does  not  conform  well  to  the  contour,  grind  the 
porcelain  to  the  required  form  and  polish  its  surface.  Place  the  ve- 
neer in  the  muffle  of  the  furnace  and  heat  to  a  point  that  will  re-gloss  the 
porcelain,  which  will  be  about  2300°  F.,  then  reapply  the  veneer  to  the 
cap.  A  slight  space  should  be  left  between  it  and  the  shoulder  at  the 
point  S. 

The  veneer  and  cap  are  washed  clean,  replaced  on  the  die,  and  the 
veneer  is  secured  in  position  on  the  cone  with  a  small  piece  of  wax 
placed  on  the  Hngual  side  (Fig.  11 08).  Porcelain  body  mixed  thin  is 
applied  first  on  one  side  and  then  on  the  other,  the  die  being  slightly 
jarred  and  the  moisture  absorbed  by  blotting  paper. 

For  the  first  bake,  at  least,  no  body  should  be  placed  in  the  groove 
at  the  shoulder,  GG,  Fig.  11 09.     The  wax  is  removed  from  the  back  of 


FiG.  1106.  Fig.  1107.  Fig.  1108. 

the  veneer  by  softening  it  with  a  heated  instrument,  and  the  cap  and 
veneer  lifted  off  the  die  by  pressure  under  the  overlap  shoulder  with  a 
pointed  instrument,  and  placed  on  pulverized  silex  on  a  slab  with  the 
face  of  the  veneer  resting  on  the  silex,  as  shown  in  Fig.  mo.  The 
first  bake  should  be  only  a  low  biscuit  bake,  which  will  not  cause 
adhesion  of  the  silex  to  the  veneer.  Heat  the  crown  very  slowly  or  the 
moisture  will  form  steam  and  blow  or  separate  the  cap  from  the 
veneer.  Gradually  move  the  crown  into  the  muffle.  When  biscuited 
and  cool,  adjust  the  crown  on  the  die:  correct  any  changes  caused  by 
shrinkage  in  the  baking  and  again  burnish  the  platinum  into  the  groove 
around  the  shoulder.  Apply  additional  body  sufficient  to  give  the 
crown  the  desired  form  and  a  slight  excess  to  allow  for  shrinkage. 
Pass  the  point  of  a  fine  broach  or  needle  around  the  surface  to  leave 
a  minute  space  between  the  body  and  the  platinum. 

Stand  the  crown,  this  time  upright  on  the  silex,  and  give  it  a  good 
biscuit  bake.  On  removal,  again  adjust  on  the  die  and  burnish  the 
platinum  at  the  shoulder.     Fill  in  the  seam  at  the  shoulder  with  body. 


538  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

and  elsewhere  if  needed,  and  give  the  crown  the  fusing  or  final  bake. 
Fig.  mi  shows  the  crown  before  the  matrix  is  removed. 

Formation  of  Porcelain  Crown  without  a  Veneer. — Place  the  cone 
on  the  die  and  apply  and  shape  over  the  entire  surface  to  the  desired 
form  of  the  crown.  Next  with  the  point  of  a  thin  spatula,  cut  a  groove 
between  the  porcelain  body  and  the  platinum  forming  the  shoulder, 
entirely  around  the  cone,  as  shown  at  GG,  Fig.  iioo,  to  prevent  shrink- 
age in  the  first  baking  from  drawing  the  platinum  at  that  point.  Re- 
move the  cone  from  the  die  and  set  upright  with  the  shoulder  resting 
on  silex  on  a  tray,  and  bake.  After  baking,  adjust  on  die  and  burnish 
at  the  shoulder.  Apply  more  body,  fill  in  seam  at  shoulder  and  give 
second  baking.  Again  adjust  on  die,  apply  any  necessary  body  and 
give  the  final  or  fusing  bake,  which  should  gloss  the  surface  properly. 

Removal  of  Matrix  or  Cone. — The  matrix  or  cone  is  removed  by 
pulling  from  the  edge  with  stiff  pointed  tweezers.     This   should  be 


Fig.  iiio.  Fig.   iiii. 

done  carefully  so  as  not  to  fracture  the  porcelain  edge;  avoid  especially 
letting  the  tweezers  slip. 

Cementation. — Before  cementing,  etch  the  cavo-surface  of  the 
crown  with  hydrofluoric  acid  to  afford  a  better  adhesion  for  the  cement. 
The  cement  should  be  mixed  to  the  consistence  of  a  thick  cream,  which 
will  not  require  much  force  to  bring  it  to  position  on  the  tooth.  The 
setting  should  be  done  with  a  slight  rotary  motion  to  allow  the  excess 
to  press  out.  The  crown  when  set  should  be  held  under  pressure  for 
at  least  five  minutes. 

The  Overlap  Crown 

This  consists  of  a  porcelain  facing  that  covers  the  labial  surface 
and  overlaps  the  approximal  sides  and  incisal  portion  of  a  natural 
crown,  leaving  the  lingual  side  uncovered.  It  is  applicable  to  special 
cases  of  defective  labial  surfaces. 

The  labial  side  and  incisal  edge  of  the  natural  tooth  are  first  trim- 
med as  shown  in  Fig.  in 2,  and  the  approximal  sides  as  represented  in 
Fig.  1 1 13.  A  matrix  of  platinum  foil  ^ooo  is  shaped  to  fit  the  trimmed 
section  extending  around  on  the  sides  for  stability.     A  very  thin 


PORCELAIN  AND  PLATINUM  CROWN-WORK 


539 


veneer  is  fitted  to  the  labial  section  and  first  attached  with  body.     The 
sides  are  then  shaped  in  three  bakings. 

Another  method  is  to  form  the  entire  crown  of  the  porcelain  body 
alone  without  a  veneer.  After  the  first  baking  correct  any  changes 
caused  by  shrinkage  in  the  baking,  again  burnishing  the  platinum  into 
the  grooves  around  the  shoulder.  A,  Fig.  1112,  shows  the  labial  aspect 
of  such  a  crown  or  facing  and  B,  Fig.  11 13,  a  side  view.  Fig.  11 14 
shows  the  finished  overlap  crown. ^ 


Pig.  1113. 


Fig.   1 1 14. 


Crowning  of  Roots  Decayed  .Apart  at  the  Bifurcation 

The  crowning  of  roots  decayed  apart  at  the  bifurcation  is  better 
accomplished  with  platinum  and  porcelain  than  by  any  method  with 
gold.     The  method  of  procedure  is  as  follows:  The  sides  of  the  roots 


Fig. 


1115. 


Pig.  1116. 


are  trimmed  in  parallel  lines  and  then  slightly  tapered  well  under  the 
gum  margin,  as  shown  in  Fig.  11 15.  Platinum  collars,  gage  38  to  40 — 
the  lighter  gage  for  very  small  roots — are  made  for  each  root  and  a  floor 
added  of  platinum,  gage  No.  36.  A  plaster  impression  is  taken  that 
will  remove  the  caps  in  position.  A  model  is  run  of  investing  material 
and  the  impression  removed.  The  two  caps  are  joined  together  with  a 
^  Suggested  by  Dr.  C.  H.  Land  and  described  also  by  Dr.  W.  A.  Capon. 


540  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

bar  of  platinum  wire — the  ends  slightly  flattened — extended  across 
the  floor  of  each  cap,  and  soldered  with  pure  gold  or  platinum  solder  as 
shown  in  Fig.  1116. 

The  united  caps  are  fitted  on  the  roots  and  a  combined  "bite"  and 
impression  taken  in  compound.  A  little  of  the  compound  should  be 
placed  between  the  caps  so  that  it  will  press  on  the  gum  septum.  The 
caps  are  veneered  inside  with  paraflin,  and  a  plaster  model  and  articu- 
lation made.     The  united  caps  are  then  removed  and  cleaned. 

Using  the  caps  and  bar  as  a  foundation,  a  porcelain  crown  is  formed. 
This  is  facilitated  by  first  encircling  the  caps  with  a  matrix  of  Hooo 
platinum  and  shaping  it  to  the  form  of  the  required  crown.  It  should 
be  burnished  over  and  against  the  occlusal  third  of  the  approximal 
teeth  if  present,  to  insure  a  knuckling  of  the  finished  crown,  as  shown  in 
Fig.  1 1 17.  The  matrix  formed  by  this  band  is  filled  with  a  very  high- 
fusing  body  and  baked.  The  porcelain  body  should  be  given  only  a 
biscuit  bake  until  the  form  of  the  occlusal  surface  and  the  other 
parts  is  definitely  shaped,  then  the  final  bake  can  be  given.     The  porce- 


FiG.  1117.  Fig.  1118. 

lain  body  should  be  placed  under  the  bar  between  the  caps  at  the  point 
A,  so  that  the  porcelain  in  the  finished  crown  shall  press  on  the  septum 
of  the  gum  there  and  prevent  invasion  of  particles  of  food.  Sufficient 
of  the  plaster  of  the  model  should  be  removed  at  this  point  to  admit 
of  the  apphcation  of  porcelain  and  not  interfere  with  the  adjustment 
of  the  crown  on  the  model  during  the  construction.  On  removal  of  the 
matrix  any  imperfect  points  may  be  trimmed  and  polished  or  added  to 
with  a  lower-fusing  porcelain  body.  Fig.  1 1 1 8  shows  the  finished  crown . 
The  presence  of  the  porcelain  that  touches  or  presses  on  the  tissues 
will  be  benignly  accepted  by  them  and  they  will  contract  around  it. 

Commenls  on  Grades  of  Porcelain 

The  success  of  many  operations  depends  on  the  grade  of  porcelain 
used.  Proportionately  the  higher  the  fusing-point  of  a  porcelain,  the 
better  it  maintains  its  integrity  in  the  mouth.  The  low-fusing  body 
that  is  used  in  inlay-work  on  account  of  its  easy  manipulation,  is 


PORCELAIN  AND  PLATINUM  CROWN-WORK  541 

entirely  unsuited  for  operations  in  crown-work.  The  use  of  a  high- 
fusing  body  as  a  foundation  and  finishing  with  a  lower-fusing  simplifies 
the  construction  but  detracts  from  the  strength. 

The  strongest  dental  porcelain  is  that  used  in  the  manufacture  of 
artificial  teeth.  To  obtain  in  crown-work  an  equal  strength,  the  same 
body  must  be  used  and  sufficient  heat  applied  to  fuse  it. 

Compounding  Artificial  Tooth  Body.' — Porcelain  tooth-body  suit- 
able for  this  work  is  obtained  by  selecting  diatoric  teeth  of  classified 
shades  and  finely  pulverizing  them  in  a  wedgewood  mortar.  The 
teeth  of  each  shade  are  first  crushed  into  small  pieces  and  those  forming 
the  blue  and  yellow  sections  of  the  tooth  separated  and  ground  sepa- 
rately in  a  wedgewood  mortar.  When  pulverized,  the  two  shades  of 
the  body  should  be  placed  in  separate  boxes  and  labeled  according  to 
the  shade.  New  shades  may  be  made  by  mixing  the  same  as  described 
in  the  lower-fusing  bodies. 

In  the  formation  of  an  entire  crown  with  this  body,  yellow  is 
used  as  the  foundation  and  blue  chiefly  for  the  surface  and  cusps. 
When  a  veneer  is  used,  the  body  is  correspondingly  applied  under  and 
around  it. 

The  advantages  of  the  use  of  porcelain  teeth  in  this  manner  are: 

1.  The  greatest  possible  strength  of  the  porcelain  is  assured. 

2.  There  is  less  shrinkage. 

3.  When  used  in  connection  with  a  porcelain  veneer  there  is  less 
liability  of  cracking  it,  as  the  shrinkage  of  the  veneer  and  body  is  the 
same. 

4.  It  withstands  repeated  fusings  better. 

For  the  reasons  enumerated,  artificial  tooth  body  is  preferable 
for  use  in  porcelain  crown-work,  especially  for  jacket  crowns  made 
entirely  of  the  body,  and  overlap  crowns. 

1  Method  suggested  by  Dr.  Land. 


PART  VII 

CROWN-,  BRIDGE-  AND  PORCELAIN-WORK 

COMBINED  WITH  OPERATIVE  DENTISTRY 

IN  DENTAL  PROSTHESIS 


CHAPTER   I 
OPERATIONS  IN  DENTAL  PROSTHESIS 

SYMMETRY — CASES  SHOWING  THE  RESULTS  OF  COMBUSTED  OPERATIONS 
— GOLD  AND  PORCELAIN  SANITARY  BRIDGE — COMBINED  ROOT  AND 
CROWN  REPLACEMENT  WITH  PORCELAIN — INLAY  RESTORATION  IN  A 
CLOSE  INCISAL  OCCLUSION 

In  crown-  and  bridge-work,  artistic  skill  on  the  part  of  the  operator 
can  frequently  be  most  advantageously  displayed  in  the  conduct  of 
operations.  An  appearance  of  symmetry  should  be  imparted  as  much 
as  possible  to  the  upper  front  teeth.  The  contour  of  the  arch,  the 
labial  aspect  and  length  of  the  teeth,  singly  and  collectively,  on  one 
side  of  the  mouth  in  comparison  to  those  on  the  other,  should  be  ob- 
served and  studied.  That  most  appreciable  results  are  thus  possible 
of  attainment  is  demonstrated  in  the  following  two  cases: 

Symmetry. — In  the  case  presented  in  Fig.  1119,  that  of  a  gentleman 
of  about  sixty-two  years  of  age,  is  to  be  seen  the  irregularity  of  the 
teeth  present  and  the  unevenness  of  their  incisal  edges  and  occluding 
surfaces,  the  condition  having  arisen  from  the  combined  effects  of  decay, 
erosion,  mechanical  abrasion,  and  malocclusion.  The  operations 
performed  were  as  follows:  On  the  right  side  the  second  molar  was 
restored  by  filling;  the  first  molar  and  the  bicuspid  crowned  with  gold; 
the  cuspid  and  central  were  lengthened  with  solid  gold  tips,  each  tip 
being  anchored  with  three  pins;  and  the  lateral  was  crowned — at  the 
request  of  the  patient — with  gold.  On  the  left  side  the  central  was 
crowned  with  a  gold  crown  with  porcelain  front,  the  cuspid  shortened 
and  filled  on  the  palatal  side,  and  the  bicuspid  crowned  with  gold  and 
the  spaces  bridged. 

Guided  by  a  line  at  right  angles  to  the  median  line  (Figs.  1119  and 
1 1 20),  the  teeth  and  crowns  on  one  side  were  formed  to  correspond  as 
much  as  possible  in  length,  shape,  and  appearance  to  those  on  the  other. 
Those  teeth  affected  with  pyorrhea  were  treated.  The  results  of  these 
combined  operations,  conducted  with  a  view  to  the  artistic  as  well  as 
the  restorative  effect,  are  plainly  to  be  seen  in  the  finished  case  illus- 
trated in  Fig.  1 1 20. 

What  can  be  quickly  accomplished  by  judicious  trimming  and  shap- 
ing of  the  teeth,  in  combination  with  other  operations,  is  well  illus- 

35  545 


546 


CROWN-,  BRIDGE-,  AND  PORCELAIN -WORK 


trated  in  the  following  case:  The  patient's  upper  front  teeth  presented 
the  appearance  shown  in  Fig.  1121.  The  right  central  and  left  lateral 
were  pulpless.     The  central  was  badly  discolored  and  the  lateral  slightly 


Fig.   1119. 

SO.     The  central  had  been  bleached,  but  in  a  few  years  gradually  re- 
sumed its  former  appearance.     The  other  teeth  with  living  pulps  and 


Fig.  1120. 


light  in  color  contrasted  most  unfavorably.     The  incisal  edges  of  the 
centrals  were  affected  with  atrophy.     The  laterals,  especially  the  right 


Fig.   II2I. 


Fig.   1122. 


one,  were  elongated  from  pyorrhea.  The  length  of  the  incisors 
contrasted  unfavorably  with  the  cuspids.  The  patient,  a  lady,  was  so 
annoyed   at  the    appearance    of  the    teeth,   which  she  considered  a 


OPERATIONS  IN  DENTAL  PROSTHESIS 


547 


permanent  disfigurement,  that  she  had  positively  decided  to  have  all 
the  incisors  crowned  or  extracted  and  artificially  replaced.  A  most 
satisfactory  compromise  was  effected,  enabling  the  patient  to  avoid 
either  of  these  extreme  measures  by  the  performance  of  the  following 
operations:  The  pyorrhea  was  treated,  the  left  lateral  was  bleached 
and  refilled,  the  right  central  natural  crown  excised  and  an  artificial 
one  inserted,  and  the  atrophied  incisal  edge  of  the  left  central  removed, 
all  the  incisal  ends  of  the  other  teeth  being  trimmed  to  properly 
correspond  in  length  and  shape.  The  improvement  effected  is  apparent 
in  the  illustration  of  the  finished  case,  Fig.  1122. 

The  method  of  procedure  respecting  trimming  and  shaping  as 
described  in  these  cases  might  often  be  applied  advantageously  in 
cases  of  fracture  of  the  incisal  edge  of  front  teeth  too  small  to 
reliably  restore  with  porcelain. 


Fig.  I 123. 


The  results  in  dental  prosthesis  which  can  be  accomplished  by  a 
combination  of  operations  on  the  natural  teeth  with  crown-  and  bridge- 
work  commend  the  plan  strongly  to  the  experienced  practitioner.  A 
few  more  cases  are  adduced  in  illustration. 

Cases  Showing  the  Results  of  Combined  Operations. — A  case 
which  was  interesting,  owing  to  the  conditions  presented  and  the  various 
operations  connected  with  it,  is  illustrated  in  Fig.  1 1 23.  Fig.  1 1 24  shows 
the  methods  and  operations  practiced,  and  Fig.  11 25  the  case  completed. 

The  upper  front  teeth  show  the  effects  of  abrasion  on  the  incisal 
edges  and  occluding  surfaces.  The  bicuspids  and  molars  were  affected 
with  pyorrhea  alveolaris.  The  four  incisors  and  the  left  cuspid  were 
pulpless,  and  alveolar  abscess  existed  at  the  roots  of  three  of  the  in- 
cisors.    The   abscesses   and   root-canals  were  properly  treated.     Gold 


548 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


collar  crowns  with  porcelain  fronts,  having  flat  incisal  edges  which 
perfectly  protected  the  porcelain  fronts  and  slightly  opened  the  bite, 
were  made  for  the  incisors  and  left  cuspid  (Fig.  1124).  The  bicuspids 
and  molars  were  placed  in  as  hygienic  a  condition  as  possible  by  treat- 
ment. On  the  left  side  a  dummy  bicuspid  with  a  bar  which  fitted  in 
a  slot  formed  to  receive  it  in  the  occluding  surface  of  the  second  bi- 
cuspid was  attached  to  the  cuspid  crown.  When  the  cuspid  crown  with 
the  dummy  bicuspid  was  cemented  in  position,  the  bar  was  anchored 
in  the  slot  in  the  second  bicuspid  with  amalgam.  The  cuspid  root  being 
very  firm,  stability  was  thus  imparted  to  the  natural  bicuspid,  which 
was  quite  loose  because  of  absorption  of  its  socket.  On  the  right  side 
the  second  biscuspid  was  entirely  capped  with  a  gold  seamless  crown. 


Fig.   1124. 

On  the  anterior  side  of  this  gold  crown  an  artificial  toofh  was  attached 
as  a  dummy  first  bicuspid,  with  a  bar  extending  from  its  anterior  side 
and  fitted  into  a  slot  formed  in  the  incisal  surface  of  the  natural  cuspid 
crown.  From  the  posterior  side  of  the  second  bicuspid  gold  crown  a 
bar  was  extended  backward  into  the  side  of  the  molar.  When  the  gold 
crown  was  cemented  in  position  on  the  second  bicuspid,  the  anterior 
bar  was  firmly  anchored  in  the  cuspid  with  a  gold  filling,  which  also 
lengthened  the  incisal  edge,  and  the  posterior  bar  was  fixed  in  the  molar 
with  amalgam.  The  reasons  for  this  form  of  construction  were:  The 
second  bicuspid  was  very  loose  in  its  socket,  and  the  molar,  though 
comparatively  more  stable,  was  also  similarly  affected.  The  attach- 
ment of  the  bar  in  the  cuspid  supported  the  dummy  bicuspid  and 
steadied  the  second  bicuspid,  and  the  extension  of  the  posterior  bar  into 


OPERATIONS  IN  DENTAL  PROSTHESIS 


549 


the  molar  likewise  afforded  additional  support  to  the  bicuspid.  The 
pulp  of  the  molar  being  exposed,  was  devitalized,  removed  and  the 
canals  properly  filled.     Fig.  1125  shows  the  completed  case. 

The  lower  teeth,  in  comparison  with  the  upper,  were  but  slightly 
abraded.     The  cuspids  and  one  of  the  incisors  were  tipped  with  gold. 


Fig.  1125. 

The  molars  on  the  left  side  were  absent,  so  that  bridge-work  on  the 
upper  jaw  on  that  side  between  the  bicuspid  and  molar  would  have  been 
to  no  purpose. 

Fig.  1 1 26  illustrates  a  case  as  presented  for  treatment. 

The  loss  of  the  posterior  teeth  of  the  lower  jaw  and  the  abrasion 
of  the  anterior  teeth  had  resulted  in  the  abnormal  occlusion  shown. 


Fig.   1126^ 


The  incisal  edges  of  the  lower  teeth  were  lengthened  with  gold  contour 
fillings.  Gold  collar  crowns  with  porcelain  fronts  were  placed  on  the 
upper  anterior  teeth,  to  lengthen  them  sufficiently  to  restore  the  oc- 
clusion. The  upper  molars,  which  were  all  more  or  less  decayed  and 
broken  down,  were  restored  in  form  with  gold  crowns.     The  space  rep- 


55° 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


resenting  the  loss  of  the  left  bicuspid  was  filled  with  a  bridge  tooth 
having  a  porcelain  front,  attached  to  the  approximal  gold  crown.  In 
the  lower  jaw  a  partial  set  was  inserted  on  each  side  to  substitute  the 
lost  posterior  teeth.  Fig.  1127  shows  the  appearance  of  the  case  when 
completed. 


Fig.   1127. 


Gold  and  Porcelain  Sanitary  Bridge 

In  the  case  presented  in  Fig.  1 1 28  the  loss  and  long-continued  absence 
of  the  inferior  right  second  cuspid  and  first  molar  caused  the  occluding 
teeth  to  elongate  and  the  inferior  incisors  to  occlude  so  forcibly  on  the 
lingual  side  of  the  superior  incisors  as  to  slightly  spread  them.  The 
patient  consented  to  the  artificial  restoration  of  the  bicuspid  and  molar, 
but  only  on  condition  that  no  considerable  mutilation  of  the  abutment 
teeth  should  be  necessary. 

Sufficient  space  for  the  collar  of  a  cap  for  the  first  bicuspid  on  the 
mesial  side  was  obtained  by  wedging  and  a  slight  removal  of  the  con- 
tour. The  distal  side  was  removed  sufficiently  to  parallel  it.  At  the 
occlusal  surface  space  for  the  presence  of  a  cap  was  obtained  by  remov- 
ing a  portion  of  the  cusps  and  a  goodly  part  of  the  surface  of  a  filling 
in  the  antagonizing  tooth.  As  the  second  molar  tipped  forward,  its 
distal  side  needed  very  little  trimming,  but  the  mesial  surface  required 
quite  a  little  reduction  to  bring  it  suflSiciently  in  line  with  the  first  bi- 
cuspid. On  the  occlusal  surface  the  cusps  were  reduced  and  consider- 
able material  ground  off  the  surface  of  a  large  amalgam  filHng  in  the 
occluding  superior  molar. 

Impressions  were  next  taken  of  the  occlusal  surface  and  sides  of 
the  bicuspid  and  molar  and  short  caps  were  struck  up  of  pure  platinum, 
gage  No.  T,&,  trimmed  to  a  depth  and  form  at  the  sides  that  would  per- 
mit them  to  be  inserted  and  removed  when  united  to  the  bridge.  Over 
the  occlusal  surfaces  of  these  caps  were  melted  and  flowed  a  few  par- 
ticles of  pure  gold,  enough  only  to  sHghtly  modify  the  color  of  the  plati- 


OPERATIONS  IX  DESTAL  PROSTHESIS  551 

num.  Next  over  the  surface  of  the  caps  supplementary  caps  of  3^500 
platinum  were  struck.  These  supplementary  caps  were  trimmed 
one-sixteenth  of  an  inch  smaller  at  the  edges  and  then  perforated  with 
punch  forceps  and  re-swaged  over  the  first  caps.  The  caps  were  then 
subjected  to  a  white  heat  with  the  blowpipe,  which  caused  the  film  of 
pure  gold  on  the  surface  of  the  first  cap  to  unite  them.  The  cavo-sur- 
face  of  the  caps  was  painted  with  rouge  and  clasp  gold  flowed  over  their 
surfaces  in  quantity  sufficient  to  fill  the  punch  holes  and  distribute  a 
film  over  the  entire  surface  of  each  cap.  The  edges  of  the  caps  were 
trimmed  and  polished,  then  cleaned  and  again  swaged  to  remove  any 
contraction  from  the  soldering. 

A  hole  was  drilled  in  the  deepest  fissure  of  the  occlusal  surface  of 
each  tooth  through  the  cap  and  a  roughened  wire  fitted  and  soldered 
in  position.  The  caps  were  next  adjusted  on  the  teeth,  a  "bite"  in 
wax  first  taken  and  then  an  impression  of  plaster,  which  removed  the 
caps  in  position,  and  models  were  made.     A  sanitary  gold  and  porce- 


FlG.    1128. 

lain  bridge  was  then  constructed,  as  described  in  Part  IV,  Chapter  III. 
When  the  bridge  was  cemented,  the  edges  of  the  caps  were  burnished 
against  the  enamel.  Subsequently  when  the  cement  was  thoroughly 
set,  a  small  fine-grained  finishing  point  was  run  over  the  edge  and  the 
surface  additionally  polished  and  burnished. 

To  render  the  edges  of  the  caps  quite  imperceptibe  to  the  tongue : 
In  the  construction  when  the  edges  of  the  caps  have  been  trimmed  to 
the  desired  form,  dry  the  surface  of  the  tooth  and  mark  the  lines  of 
the  edge  on  the  enamel.  Remove  the  caps  and  grind  the  enamel  so 
as  to  slightly  indent  it  to  but  beyond  the  line  of  the  pencil  mark.  Burn- 
ish the  edge  of  the  cap  into  this  groove. 

Fig.  1 128  shows  the  bridge  viewed  from  the  buccal  side  and  Fig. 
1129a  radiograph  from  the  lingual.  The  porcelain  base,  also  the  labial 
and  lingual  sides  of  the  dummies  are  incorruptible  and  their  form  is 
very  acceptable  in  feeling  to  the  tongue.  Proper  use  of  a  pointed  brush 
and  floss  silk  will  insure  a  hygienic  condition  of  the  mouth. 


552 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


Cast  partial  cap-crowns  described  in  Part  IV,  Chapter  IV,  may  be 
used  instead  of  the  stamped  cap-crown. 


Fig.   1129. 

The  case  shown  in  Fig.  1130  demonstrates  the  use  of  a  combined 
inlay  and  partial  cap.  A  lady  patient  lost  the  right  first  and  second 
superior  bicuspids.     She  wished  to  remedy  this  vacancy,  which  ma- 


FiG.  1 130. 


terially  disfigured  an  otherwise  good-appearing  set  of  teeth.\  The  oc- 
cluding teeth  on  the  lower  jaw,  owing  to  the  absence  for  many  years  of 


Fig.   1131. 

the  upper  antagonizing  ones,  had  elongated,  and  gave  but  little  room  for 
an  occluding  surface  for  the  artificial  substitutes.  Under  the  conditions 
present,  and  the  fact  that  the  paitent  only  desired  to  improve  the  ap- 


OPERATIONS  IN  DENTAL  PROSTHESIS 


553 


pearance  and  declined  to  allow  the  cuspid  to  be  cut  into  for  support, 
the  author  constructed  an  extension  bridge,  supported  by  an  inlay, 
which  contained  three  pins  and  partly  capped  the  mesial  side  of  the 
molar.  The  mesial  pins  were  of  gage  20.  The  distal  pin,  gage  17, 
was  inserted  as  deeply  into  the  posterior  section  of  the  dentin  as  it 
could  be  placed  without  endangering  the  pulp,  to  obtain  a  secure  at- 
tachment and  resist  the  leverage  exerted  by  the  bridge.     A  lug  rested 


Fig.  1132. 

on  the  lingual  side  of  the  cuspid.  Fig.  1131  shows  the  construction, 
H  the  position  of  the  holes  for  the  pins  and  cavity  to  receive  the  inlay, 
and  the  line  of  the  partial  cap.  P  illustrates  the  line  of  the  two  mesial 
pins  and  also  the  partial  cap.  Fig.  113  2  is  a  radiograph  taken  nine 
years  after  the  operation. 

Combined  Partial  Root  and  Crown  Replacement  with  Porcelain. 
Partial  root  replacement,  as  well  as  root  crowning,  was  involved  in  the 


Fig.  1133. 

case  shown  in  Fig.  1133,  a  left  inferior  molar  the  roots  of  which  were 
decayed  apart  at  the  bifurcation.  An  examination  showed  the  mesial 
root  suitable  for  capping,  but  the  distal  was  destroyed  by  decay  to  the 
edge  of  the  alveolus,  a  condition  in  the  case  of  a  molar  that  seemed  to 
preclude  the  possibility  of  a  crowning  operation  on  both  roots.  When 
the  patient  was  so  informed  she  made  an  urgent  plea  that  some  plan 
be  devised  to  retain  and  utilize  both  roots  and  artificially  restore  the 
crown. 


554  CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 

The  operation  performed  in  detail  is  as  follows:  Both  root-canals 
were  found  to  be  entirely  calcified.  The  sides  of  the  mesial  root  and 
the  projecting  end  were  trimmed  to  slightly  taper,  a  post  was  inserted 
in  the  root  for  stability  and  a  closely  fitting  collar  of  pure  platinum,  gage 
No.  ;^S,  was  made.  The  decay  on  the  end  of  the  distal  root  when  re- 
moved disclosed  that  the  remainder  of  the  dentin  was  dense  and  the 
root-canal  completely  calcified.  As  the  patient  refused  to  have  a 
radiograph  taken,  a  hole  was  drilled,  guided  by  the  position  and  ap- 
parent shape  of  the  root,  deep  and  large  enough  to  receive  and  anchor 
a  closely  fitting  iridio-platinum  post,  about  gage  15,  that  had  previously 
been  rolled  under  a  file  to  roughen  it.  By  means  of  several  packings 
of  gutta-percha  the  end  of  the  root  was  fully  exposed.  The  post, 
surrounded  with  impression  compound,  was  introduced,  an  impression 
of  the  end  taken  and  an  amalgam  die  made  with  the  post  in  position. 
By  means  of  this  die,  the  post  having  been  removed,  a  plate  for  the  end 
of  the  root  was  made,  its  center  punctured  and  the  post  inserted,  ce- 
mented with  wax,  removed  and  soldered  to  the  floor  with  a  particle 


Fig.   1 134.  .  Fig.   1135. 

of  pure  gold.  The  edge  of  the  plate  was  trimmed  uniformly  even  with 
the  edge  of  the  end  of  the  root.  The  post  and  floor  were  adjusted  ori 
the  root  and  the  extension  of  the  post  slightly  bent  to  parallel  it  with 
the  line  of  the  sides  of  the  mesial  root. 

On  the  floor  and  around  the  post  a  porcelain  extension  of  the  root 
parallel  with  the  mesial  root  collar  was  made  of  high-fusing  porcelain 
body,  using  a  platinum  foil  matrix  that  was  removed  when  the  baking 
was  completed  (Fig.  1134).  A  platinum  collar  was  made  for  the  porce- 
lain root  extension  similar  to  the  one  for  the  mesial  root.  The  porce- 
lain extension  to  the  root  was  then  divested  of  the  collar,  cemented  on 
the  root  and  allowed  to  remain  a  week  for  the  membrane  of  the  gum  to 
contract  and  assume  normal  position  upon  it.  The  platinum  collar 
was  adjusted  and  the  cervical  portion  trimmed  to  leave  a  space  of  one- 
sixteenth  inch  between  the  edge  of  the  collar  and  the  gum  margin. 
The  ends  of  the  two  collars  were  trimmed  even  and  the  floors  added. 
The   two  caps  were  then  connected  with  a  bar  (Fig.  1135),  and  the 


OPERATIONS  IN  DENTAL  PROSTHESIS 


555 


crown  section  made  with  the  porcelain  pressing  on  the  septum  of  gum 
between  the  roots  (A),  as  described  in  Part  VI,  Chapter  VIII  (Figs. 
1115  to  1118). 

Fig.  1 136  shows  the  completed  crown  and  Fig.  1137,  a  radiograph 
which  the  patient  finally  consented  to  have  taken  about  six  years  subse- 
quent to  the  operation. 

In  cases  where  pyorrhea  alveolaris  exposes  the  bifurcation  between 
the  roots  of  a  molar,  forming  a  pocket  which  fills  with  extraneous  matter 


Fig.   1136. 


Fig.  1137. 


and  consequently  acts  as  an  incentive  to  the  destruction  of  the  investing 
membranes,  the  author  has  quite  effectively  retarded  the  progress  of 
the  disease  by  the  following  treatment,  described  as  practiced  on  a 
lower  molar.  In  this  case  a  pocket  had  formed  between  the  roots  from 
disintegration  and  absorption  of  the  tissues  in  such  a  manner  as  to 
leave   an  open  space  that  it  was  not  possible  to  keep  clean.     As  the 


Pig.  I 138. 


Fig.   1139. 


tooth  was  pulpless,  a  cavity  was  made  at  an  angle  in  an  occlusal  direction 
as  shown  in  section  at  A,  Fig.  1138,  of  a  size  and  shape  sufficient  to 
receive  and  retain  a  porcelain  inlay  that  would  fill  the  cavity  and  also  the 
open  space  between  the  roots,  as  shown  in  Fig.  1139.  The  pocket  being 
thus  removed,  the  tissues  contracted  over  the  part. 

Inlay  Restoration  in  a  Close  Incisal  Occlusion. — In  cases  of  fracture 
of  the  incisal  edge  of  a  central  incisor,  for  example  as  shown  in  Fig.  1140, 


556 


CROWN-,  BRIDGE-,  AND  PORCELAIN-WORK 


where  a  close  occlusion  or  "bite"  exists,  as  indicated  in  Fig.  1141,  ar- 
tificial restoration  of  the  part  can  generally  be  .best  effected  by  the  use 
of  a  gold  inlay  for  stability,  faced  with  one  of  the  silicate  cements  or 
porcelain  for  appearance. 

In  the  case  shown  in  Fig.  1 140  a  secure  anchorage  was  obtained  for 
the  gold  inlay  by  its  insertion  in  a  linguo-labial  direction  by  forming  an 
anchorage  in  the  lingual  side,  as  shown  in  Fig.  1142.     A  portion  of  the 


Fig.   II  40. 


Fig.   1141. 


wax  on  the  labial  side  of  the  wax  model  of  the  inlay  was  removed  (A, 
Fig.  1 143).  When  the  casting  was  made  and  fitted,  the  gold  was 
removed  so  as  to  form  a  labial  cavity  with  an  undercut  edge  suitable 
for  a  silicate  cement  filHng.  The  straight  mesial  wall  of  the  fracture 
formed  the  distal  side  of  the  cavity  for  the  filHng.  After  the  gold  inlay 
was  cemented  to  position  and  the  cement  had  set,  the  surplus  cement 


Fig.   1142. 


Fig.  1143. 


that  oozed  into  the  cavity  formed  for  the  filling  was  removed  and  a 
silicate  filling  inserted.  In  course  of  time  when  the  silicate  cement 
becomes  impaired  in  condition  or  shade,  it  can  be  easily  removed  and 
renewed. 

In  the  case  described  if  porcelain  is  inserted  instead  of  silicate 
cement,  the  gold  inlay  requires  to  be  cast  of  gold  alloyed  with  enough 
platinum  to  insure  against  its  melting  in  the  fusing  of  the  porcelain 


INDEX 


Abrasion  of  incisal  edges  of  teeth,  172, 

192 
method  of  forming  crown  for,  171, 

172,  192 
method  of  forming  tip  for,  232,  233, 

234 
Abutments,   retentive   and   supporting, 

274 
Abscess,  alveolar,  blind,  90 

chronic,  treatment  of,  89 
Adaptation  of  gold  collars,  146 
Adhesion  of  wax  to  gold  and  porcelain, 

IS 
Adjustable  saddle,  438,  440 
Adjustment  of  seamless  crowns,  203 
Adrenalin  and  cocain,  68 
All-gold  bridge-work,  306,  307 
collar  crowns,  149 

constructed  in  sections,  144 
seamless  crowns,  194 
All-porcelain  detached-post  crowns,  132 
Ash, 137 
Davis,  136 
Jacket,  137 
S.  S.  White,  134 
cementation  of,  139 
removal  of  excess  of  porcelain 
at  the  periphery,  138 
jacket  crown,  136,  535 
Allowance   for   contraction   of    gold   in 

casting,  217 
Alloy  for  forming   any  grade   of   gold 

solder,  10 
Alloys  of  tin,  their  use  in  crown  work, 

14 
All-porcelain  jacket  crown,  136,  538 
Alteration  of  seamless  gold  crowns,  204, 

207 
Alveolar  abscess,  classification  of,  89 
prognosis  of,  95 
treatment  of,  89 
Alveolarotomy,  91 


Amalgam,  use  in  bridge-work,  30 
Amalgam  copper,  26,  27 

in  crown-work,  30 

dies,  30 

models,  25,  26,  30 
Amputation  of  the  apex  of  a  root,  94 
Analysis  of  dentin,  63 
Anatomical  structure  of  dentin,  64 
Anchorage  bars  in  bridge- work,  319,  320 

cavity  in  a  gold  crown,  307 
Ancient  bridge-work,  269 
Anesthesia  in  pulp  extraction,  68 
Anesthetics,  local,  use  in  crown  work,  68 

154 
Annealing,  41 
Antagonizing  teeth,  preparation  of  their 

cusps,  iiQ,  113,  117,  276 
Antisepsis,  79,  81 

Antiseptic  agents  in  treatment  of  alveolar 
abscess,  93 
pulpless  teeth,  81 
Apical  foramen,  closure  of,  84 
Apicoectomy,  94 

prognosis  of,  95 
Anvil,  use  of  in  crown-work,  151 
Aristol,  use  of  in  pulp  canals,  82 
Arsenious  acid,  use  of  in  devitalization 

of  the  pulp,  90 
Articulating  impression,    24,   178,   197, 

285 
Articulation  for  bridge-work,  manner  of 

taking,  24,  285 
Articulators,  large  and  small,  20 
Artificial  crown-work,  loi 
history  of,  loi,  107 
the  gold  system,  107,  146 
the  porcelain  system,  132 
Artificial  stone,  24 
Artificial  teeth  selection  of,  15,  118,  179. 

287 
Asbestos,  33 

soldering  block,  35,  36 


557 


558 


INDEX 


Asepsis,  dependence  of  crown-work  on, 

64,  65,  118,  463 
Ash's  repair  facing,  340 

tube  teeth  and  crowns,  137 
Alrtachments,  dovetail  lug,  363 

for  removable  bridge-work,  372 
comparative  value  of,  408 
retaining  inlaj'  abutments,  392 
supporting,  398 

for  removable  bridge-work,  special 
forms  of,  400 
clasp  and  lug,  441,  444 
split  bar,  402 
winged  lug,  406 
manufactured,  463 
Chayes,  470 
Gilmore,  468 
Gollobin,  469 
Morgan,  466 
Roach,  463 
Yirikian,  475 
Atrophy  and  erosion,  192,  516 

Backings  for  porcelain  facings  in  crown 
and  bridge- work,  180,  185,  186 
use  of  sweger  for,   181 
Baking,  porcelain,  510 
Bar,   for  connecting  bridge- work,    331, 

350,  353 
Bar  attachments,  319 
"Bites,"  158,  214,  285 
Bing's  bridge- work,  271 
Black,   Dr.   G.   V.,  method  in  alveolar- 

otomy,  91 
Blow-pipe,  method  of  using,  37,  183 
carbo-hydrogen,  37 
the  S.  S.  White,  37 
Blum  split  bar  a'^tachment,  405 
Bonwill,  Gates,  porcelain  crown,  104 
Bonwill's  removable  p'ate  bridge,  443 
Borax,  method  <3i  using  in  crown  and 
bridge-work,  construction,   12, 
13,  183 
Box  backing  for  replaceable  facing,  299, 

300 
Bridge- work,  274 

abutments,     preparation     of,    274, 

278,  279,  282 
abutments,     retentive     and     sup- 
porting, 274 
adjustment  and  attachment,  293 


Bridge- work,  advantages  of,  271 
advantages  of  detachable,  362 
artistic  and  esthetic,  276 
as   affecting   hygienic   condition  of 

the  mouth,  367 
cases  illustrating,  347-456 
cast  root  caps  and  crowns  for,  210, 

282 
cementation  of,  258 
classification  of,"  277 
connecting  sections  with  bars,  331, 

350 
construction,  274,  281,  283,  295,  297 
forms  of,  273 

of  in  sections,  292,  295 
principles  involved  in,  274,  275 
criticism  of,  impartial,  272,  273 
detachable,  362 

detached  post  porcelain  crown,  323 
extension,  328,  438 
extensive  application  of  fixed,  359 
forms  of  attachments  for,  277,  278, 

282 
general  application  of  fixed,  347 

removable,  356 
history  of,  269 

how  to  cement  so  it  is  easily  re- 
moved, 265,  266  ♦ 
investing,  2,7,,  290 
Bridge-work,  manner  of  taking  impres- 
sion and  articulation,   18,   20, 
24,  285 
mechanical  principles  governing  the 
process   of  construction,    269- 
274 
Bridge-work,  methods  for  pyorrhea,  2)2)3 
models,  23 
New   York   State  Board  student's 

bridge,  40,  281,  285 
on  vital  tooth  abutments,  321 
partial   cap   and   pin   attachment, 

315, 3t6 
paralleling  of  abutments,  279,   412, 

417 

instruments,  423,  470,  475 
porcelain  detached  post-crown,  323 
porcelain  teeth  for,  276,  278 
removal  of,  342 
sanitary  fixed,  325 

porcelain  and  gold,  326 
selection  of  abutments,  277 


INDEX 


559 


Bridge- work,  variation  in  method  of  con- 
struction, 292 
versus    self-cleansing    spaces,    287, 

288 
warping  in  construction,  292 
Bridge-work,  removable,  369 
construction  of,  372,  411 
dummies  or  teeth  for,  418,  434 
forms  of  attachments  and  sup- 
ports for,  372,  441,  447 
general  application  of,  356 
impressions  and  models  for,  411, 

414,  432 
paralleling  of  abutments,  412 
post  bender,  394 
saddle,  428 

split  post  swaging  devise,  378 
vulcanite   attachment   for   teeth 
to  saddles,  440 
Brown  crown,  106 
Bryant's  method  of  repairing  fractured 

porcelain  facing,  338 
Bunsen  flame,  36,  37 

Canal,  root,  perforation  of,  96 
Cantilever  bridge-work,  330 

crown,  250 
Cap,  cup-shaped,  210 

V-shaped,  210 
Capping  pulps,  methods  of,  66 
Carmichal  crown,  312 
Cast  clasp,  446 

caps  and  crowns,  208 

inlays,  43,  228 
to  hollow,  230 
support  bridges,  229,  317 
Casting,  process  of,  43,  50 

distortion   of  wax   model,   how   to 
avoid,  53 

the  die,  29 

flasks,  44,  53 

machines,  48 

with  a  swager,  53 

saddles  and  plates,  50,  52,  461 

sanitary  bridge,  325 
Castings,  large,  50,  46 1 
Cases  of  living  pulps,  63,  66 
Cataphoresis,  68 

Cement,  advantages  of  improved  forms, 
258 

amalgam,  266 


Cement,  copper,  antiseptic,  255 

gutta-percha,  266 

oxyphosphate      and     gutta-percha 
combined,  266 

to    cause   gutta-percha,    to    adhere 
to  tooth  structure,  264,  265 

to  cause  to  set  slowly,  260 

silicate,  266 

S.  S.  White  antiseptic  silver  chlorid, 
258 

wax,  15 

zinc  oxyphosphate,  258 
Cementation  of  crown  or  bridge-work, 

258 
Charcoal  soldering  block,  35 
Chayes  attachments,  472 

parallelometer,  472 
Chronic  alveolar  abscess,  89 
Chupein  crown,  211 
Circulation  in  dentin,  63,  64 
Clasp  gold,  formula  for,  9 
Clasps,  cast,  446 
Clasps  shaping  of,  445 

swedging  of,  445 

with  lugs,  447 
Clamps,  soldering,  150 
Cleansing  of  bridge-work  when  worn  by 

patients,  367,  368 
Cocain,  use  of,  68 
Collars,  to  construct,  146 

to  contract,  151 

contouring  of,  156 

expansion  of,  157 

knuckling  of,  156,  157,  200 

bicuspids  and  molars,  147 

cusp-cap    for,    156,    159,    164, 
166,  169,  170 

hygienically  considered,  154 

incisors  and  cuspids,  171,  172,  174 

methods  of  knuckling,  and  giving 
contour,  156 

pliers,  149,  157 

preparation  of  teeth  or  roots  for,  61, 

63 
for  Richmond  crown,  146 
to  form  floor  for,  175 
Compound  blowpipe,  41 
Connecting  bars  in  bridge- work,  331,  350 
Construction  of,  bridge-work,  274,  283 

detachable  and  removable,  362, 
369 


56o 


INDEX 


Construction  of  bridge-work,  mechani- 
cal principles  governing,  274 

pfate,  441 

saddles,  428 

small  pieces  of,  297,  324,  326,  329, 
347,  348,  349,  350 

special  processes  and  appliances 

in,  305 
Contraction  of  gold  in  casting,  allowance 

for,  217 
Contour,  use  of  a  swager  to,  seamless 

crowns,  201 
Converging  teeth  and  roots  to  parallel 

in  bridge-work,  390 
Copper  amalgam  for  dies,  26,  27 
Copper,  thin  sheet,  use  of,  28 
Carborundum  wheels  and  points,   120, 

121 
Criticism  of  crown   and   bridge   opera- 
tions, 361 
Crown,  and  bridge-work  combined  with 
operative   dentistry   in   dental 
prosthesis,  545 
Crowns,  appliances  and  instruments  for, 
3,  18,  28 
approximal  contact  of,  199,  200,  250 
and  partial  root  replacement  with 

porcelain,  553 
history  of  artificial,  loi,  106 
'     Ash's  tube  teeth  and  crowns,  137 
Beers,  103 

Ronwill,  Gates,  104     • 
Brown,  106 
Cantilever,  250 
Chupein,  211 
Collar,  146 

with  porcelain  facing,  174 
cap  detached  post  crown,  213 
cup-shaped  root  cap,  210 
V-shaped  root  cap,  210 
Davis,  136 
detached  post,  132 
diatoric  porcelain  tooth  crown,  216 
Evans  gold,  200 
Foster  and  Lawrence,  103 
Gates-Bon  will,  104 
gold,  pivot,  102 
gold  with  porcelain  facing,  174 
Goslee,  213 
How,  105 
Howland-Perr}',  104 


Crowns,  Justi  shoulder  pin,  137 

Logan,  106 

Litch,  211 

Mack,  104 

MOD  and  MODL,  314 

with    malformed  occlusal  surfaces, 
no,  113,  129,  276 

Morrison  and  Beers,  103 

occlusal  surface  of,  no 

open-faced,  309,  312 

platinum  and  porcelain,  526 

porcelain,  with  a  metal  base,  141 

porcelain-faced  gold  post,  142 
Crowns,  Richmond,  102,  174 

root  end  below  gum  margin,  144 

S.  S.  White  detached  post,  213 

Staple,  314 

swaged  on  dies,  32,  198,  207 

nomenclature  of,  108 

principles  involved  in,   108 

temporary,    145 

Van  Woerts,  211 

Weston,  105 

all-gold  in  sections,  156 

contouring  of,  and  collars,  157,  200, 
201,  250 

dies  for  use  in  construction  of,  28 

finishing  and  polishing,  55 

for  abraded  teeth,  172,  192 

for  teeth  with  vital  pulps,  190,  192, 

193,  529 
gold  and  porcelain  without  a  collar, 

117,  141,  142 
gold  collar,  146 

gold  seamless  cap  incisors,  194,  196, 
198 
with   porcelain   facings,    196 
contour,  199,  201 
preparation  of  crown  or  root  for,  119 
removal  of,  342 
repair  of,  337,  346 
Crowns,  swager  for  cusp-caps,  31,  32 
Tinker,  314 

without  collars,  criticism  on,  140 
Crowning  of  molar  roots  decayed  apart 
at  the  bifurcation   with  gold, 
249 
with  porcelain,  539,  554 
Crown-work,    anatomical    and    physio- 
logical relations,  no 
approximal  contact  in,  no 


INDEX 


561 


Crown-work,  nomenclature  of,  108 

principles  involved,  117,  122 

requirements  in,  no 

shaping  teeth  and  roots  for,  119 
Cusp-buttons,  166 
Cusp-cap,  methods  of  forming,  156 

casting  of,  169 

fitting,  162,  165 

reinforcing,  161,  162,  164 

soldering,  163,  165 

swaging,  160,  161 

stamping,  161 

sweating,  to  collar,  41,  164 

Davis  crown,  136,  213 

method  of  mounting  on  caped  root, 
141,  142 
Decayed  teeth  or  roots,  special  prepara- 
tion for  crown  work,  127,  129 
Dental  furnace,  448 
Dental  lac,  15 

Dental  porcelain,  composition  of,  482 
Dental  prosthesis,  the  artistic  in,  118, 

276,  545 
Dentimeter,  147 
Dentin,  circulation  in,  63 
chemical  analysis,  63 
disinfection  of,  66 
Detached-post  collar  crowns,  213 
Detachable  bridge-work,  362 

porcelain  facing,  299 
Devitalization  of  pulps,  68 
by  cataphoresis,  68 
instantaneous,  68,  69 
,    use  of  arsenic  for,  70 
use  of  cocain  in,  68 

pressure  anesthesia  in,  68 
Diatoric  tooth  dummies,  217 
Die  plate,  168 
Dies,  28 

casting  of,  29 
counter-die  for,  29 
amalgam,  30 

Dr.  Melotte's  metal  for  dies,  14 
fusible  metal,  14 
Dimlow  facing,  304 

Diseased  pulps,  classification  of,  requir- 
ing extirpation,  66 
teeth     or     root     with    necrosis   of 
alveoli,  61 
Disinfection  of  dentin,  66 


Disinfection,   root  canals  and    dentine, 

79,81 
Disks,  forms  of,  1 20 
Dovetail-flange   and   split-post   attach- 
ment, 406 
Drills,     Gates-Gliddon,    form    of    and 

method  of  using,  76,  77,  78 
Dummies,  definition  of,  108 
how  to  form,  287,.  295 
how  to  form  of  solid  gold,  306 
in  one  continuous  piece,  326 
Dwinelle's  crown,  103 

Enamel  scalers,  122 

Electric  furnace,  use  for  baking,  488, 
491,  510 

English  bridge-work,  270 

Etching  with  acid  or  a  diamond,  512 

Electro  plating,  55,  56 
solution  for,  56 

Erosion,  use  of  porcelain  inlay  for,  516 

Evans  plate  bridge,  441,  442,  443 
gold  crown,  200 

Evslin  facing,  303 

Excision  of  natural  crown,  69 

and  instantaneous  extirpation  of 
the  pulp,  69,  348,  349 

Exit  vent  in  casting,  51 

Exostosis,  90 

Expansion  and  contraction  of  gold  and 
investing  material  in  soldering, 
9,  38,  47,  217 

Expansion  of  a  collar  or  crown,  151,  203 

Extension  bridges,  328 
leverage  in,  328 

Extension  inlay  bridge,  552 

saddle  bridges,  removable,  438 

Extensive  application  of  fixed  bridge- 
work,  359 

Extirpation  of  pulps,  68 

Facings,  different  styles  and  methods, 
178,  287 

adaptation  of,  178,  180 

backing,  180,  288 

for  metallic  crowns,  16,  178 

protection  of  incisal  edge,  179 

pointed  pin,  181 

replaceable,  299 

Ideal,  Evslin,  Stewart,  Dimlow,  301 
Files  for  metal,  4 
Filling  of  root  canals,  83,  84,  85,  86,  87 


562 


INDEX 


Finishing    and    polishing    crowns    and 

bridges,  55-183 
Fire  clay  supports  for  porcelain-work, 

526 
Flame,  structure  of,  36 
blowpipe,  36,  37 
Bunsen,  36,  37 
Floor  for  collar,  to  construct,  175 

Flux,   12 

jeweler,  liquid,  13 

Weinstien's  liquid,  13 
Fluxed  solder  fillings,  11 
Foramen,  closure  of,  83,  84 
Forceps  for  excising  natural  crown,  69 
Formalin,  81 

Formation  of  lugs,  329,  330,  302 
Formulas  for  fusible  metals,  14 

for  gold  plates  and  solders,  7 

for  platinum  solder,  1 2 
Foster  crown,  103 
Foundation    ot  basal  porcelain  bodies, 

483 
Fracture  of  porcelain  teeth  in  soldering, 

16 
Fractured  teeth  at  roots,  treatment  of, 

252 
French  bridge- work,  270 
Fusible  alloys  of  tin,  14 

Melotte's,  14 
Furnaces  for  fusing  porcelain,  488 
Fusing  of  porcelain,  492 

points  of  different  porcelains,  500 

Gas  flame,  Bunsen,  36 

Gates-Bonwill  crown,  104 

Gage  plate,  4 

General  application  of  fixed  bridge- work, 

347 
Getz,  F.  R.  bridge  attachments,  449 
Gilmore  attachment,  468 
Glutination  of  porcelain  body,  525 
Goslee  crown,  215 

Gold,  all-,  crowns  for  anterior  teeth,  171, 
198 
bicuspids  and  molars,  156,  199 
formulas  for  plate  and  solder,  7 
hollow  dummies  for  bridges,  306 
solid  dummies  for  bridges,  306,  307 
caps  seamless,  how  to  stamp,  32, 
196 
Gold  cap  crown,  to  securely  attach,  256 


Gold  casting,  method  of  allowance  for 

contraction,  217 
Gold  collar  crown,  146 

with  porcelain  facings,   174,   188 
inlay  porcelain  facing,  190 
preparation  of  teeth  for,  119 
crown  cast  on  platinum  or  gold  cap, 
208,  209 
Gold  crown  cutter,  343 
Gold  crown  metal,  7 
Gold  crown,  repair  of,  346 
Gold  cusps  for  bridge  in  one  continuous 

piece,  326 
Gold  cusps,  solid,  32,  44,  156,  169 

dummies,  306 
Gold  inlay,  28,  228 

Gold  inlay  anchorage  bar,  297,  318,  320 
Gold  inlay  formation,  43,  228 
hollowing  of,  230 
direct  method,  218 
indirect  method,  236 
impressions  for,  28,  237 
Gold  plate  lined  with  platinum,  9 
Gold  plates  and  solders,  7 
Gold  platinized,  9 
Gold  pivot  teeth,  102 
Gold  seamless  contour  crown,  200 
Gold  seamless  cap  crown,  194 

adjustment  of,  199,  203 
contouring  of,  199 
comparative  merits  of  the  sec- 
tional and  seamless  method 
of,  207 
Gold,  constructing,  collar  crowns,   146 
root  caps,  cast,  208 

seamless,  swaged,  194 
seamless  root  caps,  194 
tips  for  natural  crowns,  232,  248 
method  of  constructing,  232,  233 
Granuloma,  treatment  of,  94 
Grades  of  porcelain,  500,  540 
Gum  enamel,  porcelain,  483 

on  inlaj's,  517 
Gum   tragacanth,    use   of  in  porcelain, 

525 
Gutta-percha,  261 
cement,  262 
combined    with    oxyphosphate    for 

cementation,  266 
in  filling  root  canals,  83,  84,  86,  87 
in  preparation  of  roots,  74 


INDEX 


563 


Gutta-percha,     use    of,   for  cementing 
crown  and  bridge-work,  262 

Heat,  use  of,  as  a  disinfectant,  66,  80 
degrees   of,  in  fusing  of  porcelain, 
500 
Hollow  all-gold  dummies  for  bridges,  306 
gold  inlays,  250 
post  or  pins,  185 
wire  for  tubes,  373 
How  crown,  105 
Howland-Perry  crown,  104 
Hydrogen  peroxide,  95 
Hygienic  condition  of  the  mouth  as  af- 
fected by  bridge- work,  367 
Hygienically  considered,  collar  crowns, 
154 

Ideal  facing,  302 
Impressions,  20 

sectional,  20 
tray,  Roach,  21 

tubes,  c^ps  and  trays  for  taking,  28, 

237 
Impression  and  articulation    combined, 
24,  178,  285 
compound,  21 
for  fusible  metal  die,  28,  194 

bridge-work,    20,    23,    178,    285, 

411,  414,  429 
inlays,  28,  236 
of  crowns  or  roots,  28,  194 
materials  for  taking,  14,  20,  236 
Incisal  edge  of  porcelain  facing,  protec- 
tion of,  179 
Infection    of    zinc   oxyphosphate,    258, 

367 
Inlay  and  bar  bridge  attachment,  317 

lugs,  447 
Inlays,  218,  499 

anchorage  of,  222,  225,  227,  552 

casting  flasks  for,  44,  51,  53,  54 

expansion  and  contraction  in  mak- 
ing, 43,  47,  236 

formation  of  .wax  model,  44,  228 

dies  for,  30,  247,  248 

direct  method,  228,  505 

for  close  incisal  occlusion,  232,  555 

gold,  218 

gold  and  part  porcelain,  555 

hollowing  of  gold,  230 


Inlays,  indirect  method,  236,  509 
matrix  formation,  219,  505,  509 
porcelain,  555 

preparation  of  cavities  for,  223 
process   of   investing   heating    and 

casting,  43,  45,  48,  51,  53 
Van  Woertz's  trays  for  impression, 

239 
wax  models  of,  43,  228 
Inlaying    gold    crowns    with    porcelain 

facing,  190 
Insertion  and  cementation  of  crown  and 

bridge-work,  258,  293 
Instantaneous  extirpation  of  the  pulp, 

68,  69 
Instruments  and  materials  used  in  crown 

and  bridge- work,  3,  7,  14 
Intaglio  dies,  166 

die  made  form  wax  model,  169 
Investments  for  casting,  44,  45 

soldering,  7,7,,  34,  182,  184,  290,  295 
Iodoform  method  of  using,  85 
Iridio-platinum  plate,  7 

wire,  for  posts,  8 
Irregularities  of  the  teeth,  methods  of 

crowning  in,  250,  251 
Isinglass,    (mica),  use  of  in  crown  and 

bridge- work,  189,  406 

Jacket  crown,  porcelain,  136 
and  platinum,  529 
gold,  192 
Jenkins  low-fusing  porcelain,  509 
Jeweler's  liquid  flux,  use  of,  12,  13 
Justi  shoulder  pin  crown,  137,  213 

Knuckling  a  collar,  method  of,  156 

Large  wax  model  in  casting,  51 

Lawrence  crown,  103 

Lead  counter-dies,  method  of  forming  for 

fusible  dies,  29 
Lens  use  of,  521 
Leverage  in  bridge- work,  274,  277,  278, 

328 
in  extension  bridge- work,  328 
Litch  crown,  211 
Local  anesthesia,  119 
Locking  tweezers,  511 
Logan  crown,  106 

on  platinum  base,  534 


564 


INDEX 


Lug  with  lock  pin,  331 

Lugs  as  supports  on  artificial  crowns, 

400,  401,  444,  449 
natural  teeth,  309,  310,  316,  320, 

329.  33I)  400,  441,  446,  447,  448 

Mack  and  Howland  crown,  104 

Malformed  occlusal  surfaces,  113,  129 

Manufactured  attachments  for  remova- 
ble bridges,  463 

Materials  and  processes  used  in  crown 
and  bridge-work,  i 

Matrix  gold  inlays,  219 

Measuring  the  size  of  necks  of  crowns  or 
roots  for  collars,  147 

Melotte's  metal,  14 

Melting  and  refining  of  gold  scraps,  9 

Metallic  dies  and  counter-dies,  28 

for  forming  caps  with  cusps,  158 

Matrices,  removal  of  a  foil  matrix,  507, 

509 
Models,  23 

artificial  stone,  24 

amalgam,  26 

combination  metal  and  plaster,  29, 

136 
for  bridge-work,  23 
for  crown-work,  136,  158,  178,  197 
plaster,  to  harden,  23 
MOD  and  MODL  crowns  and  inlays, 

314 
Modern  inlays  and  their  merits,  218,  219 
Molar  roots,  decayed  apart,  method  of 

crowning,  249,  539,  554 
Moldine,  15,  29 
Mold  and  dies,  28 
Morgan    attachment    for    bridge-work, 

Morrison  and  Beers  gold  crown,  103 
Mouth,  preparation  of,  61 

Necks    or    crevices    of    teeth,    average 
forms  of,  73,  152 
methods  of  measurement,  147 
New  Richmond  porcelain  crown,  106 
Nomenclature  of  crown-work,  108 

-Objections    urged  against  bridge-work, 

272 
against  collar  crowns,  154 
against   crowns   without   collars, 

140 


Obtundents,   use  of,  in  alveolar  abscess, 
92 
in  crown  work,  119,  154 
in  extirpation  of  pulp,  68 
Occlusal  cusp-caps,  in 

of    seamless    crowns,    reinforce- 
ment of,   206 
Occlusion,  subject  of,  113,  116,  275,  276 

mal,  113,  129,  276 
Open-faced  sectional  crown,  309 
Ottolongui  root  reamers  and  facers,  133, 

134 
Overlap-crown,  538 
Oxychloride   of  zinc  in  root  and  canal 

filling,  84 
Oxyphosphate  cement,  258 

in      combination      with      gutta- 
percha, 266 
properties    suitable    for    crown- 
work,  258 
to  cause  to  set  slowly,  260 

Paralleling  instruments,  use  of,  423,  470, 

475 
Chayes,  470 
Weinstine,  423 
Paralleling  staple,  415 
Parallelodrill,   Chayes,  471 
Partial  cap  and  pin  bridge,  315 

collar  crowns,   128,   210,   211,   212, 
526 
Partial  crown-work,  inlays,  218,  501 
root    replacement    with    porcelain, 

535 

Peeso's  formulas  for  solder,  11 

Periphery,  removal  of  excess  of  porce- 
lain at,  138 

Perforation  of  the  side  wall  of  a  root 
canal,  treatment  of,  97 

Peroxide  of  hydrogen,  use  of,  95 

Physiological    relation   in    crown-work, 
no 

Pin  bender,  394 

Pivot  teeth,  102 

Plaster  and  metal  model  combined,  25 
impression  and  articulation,  method 

of  taking,  18,  24 
model,  to  harden,  23 

Plate  and  pin  attachment,  315 

Plates  and  solders,  7 

Plate  bridge,  removable,  441 


INDEX 


s(>s 


Plate  bridge,  construction  of,  450 
Plates  and  solders,  7 
Plating  outfit,  electro,  56 
Platinized  gold,  9 
Platinum,  7,  151 

advantages  in  crown-work,  7,  152 
collar,  151,  527 
foil,  7 

and  iridium,  7 
and  gold,  7 

matrix  for  fusing  porcelain,  505,  508 
Pliers  for  shaping  collars,  149,  157 
Pointed  pin  facings^  181 
Polishing    and    finishing    crown-    and 

bridge- work,  55,  256 
Porcelain  art,  dental,  481 

bodies,  character,  grade  and  com- 
pounding of,     482,  499,  540 
body  use  of  successive  grades,  516 
coloring  of,  483 
detached  post  crowns,  132 

collar  crowns,  213 
foundation  body,  483 
furnaces  for,  488 
fusing  points  of  grades,  499 
gum  enamel,  483 
ingredients,  chemical  and  ph}'sical 

character,  482 
pyrometer,  use  of  in  fusing,  491 
shades  of,  485 
shrinkage  in  fusing,  500 
teeth,   effect  of  heat  on  shade  in 
soldering,  16 
Porcelain  crowns,  ready  made,  132 

Ash's  tube  teeth  and  crowns,  137 

Davis,  136 

Justi,  137 

Logan,  106 

S.  S.  White,  134 

Jacket,  136 
method  to  facilitate  the  adapta- 
tion to  the  root,  135,  136 
method  of  selecting  and   fitting 

by  model,  135 
on  metallic  capped  roots,  141,  142 
Porcelain  and  platinum  crowns,  523 

for  teeth  witi  living^pulps,  529 
incisors  and  cuspids,  526,  529 
bicuspids  and  molars,  531,  532 
jacket  crown,  529 
tube  crown,  137,  533 


Porcelain  dental  art,  481 
Porcelain  facings  for  bridge- work,    15, 
287,  299 

backing  for,  180 

pin  pointed,  181 

protection  of  incisal  edge,  179 
Porcelain  inlays,  499,  501,  515 

direct  method,  505 

indirect  method,  569 

limitations  in,  522 
Porcelain  inlays  methods  of  etching  with 
a  diamond,  512 

points  to  bear  in  mind  regarding, 
520 
rod  method,  519 
Porcelain-faced  solid  gold  dummies,  437 
Porcelain  teeth,  15 

to  change  shape  of,  17 

selection  of,  118,  178 

Veneers,  16,  530,  537 
Porcelain  tips  to  natural  crowns,  516, 

517,  519 
Porosity  of  porcelain,  522 
Post  or  pins,  root,  in  relation  to  crowns, 

IIS,  116,  117,  143 
Posts  for  retaining  crowns,  117,  17/ 

method   of  forming   to   accurately 

fit  a  canal,  184 
hollow,  185 
Post  puller,  343 
Pouring  fusible  alloy  or  metal,  manner 

of,  14 
Preparation  of  natural  crowns  or  roots 
for  crown- work,  119 
the  mouth  for  crown-  and  bridge- 
work,  61 
Preparatory  treatment  of  the  mouth,  61 
Principles  involved  in  crown-work,  108 

in  bridge-work,  274 
Prognosis  of  chronic  alveolar  abscess,  95 
Pulp,  capping  of,  66 

diseases  of,  requiring  extirpation  65 
instantaneous,  devitalization,  68 
lesions  of,  66 

preservation  or  devitalization,  65 
use    of    arsenic    in    devitalization, 
70 
Pulp  canal  instruments,  75,  76 
Pulpless  teeth,  lesions  of,  66 

treatment  of,  72 
Pulverized  silex,  use  of,  33,  537 


566 


INDEX 


Pyorrhea  alveolaris,  bridge-work  and 
splinting  in,  ^2,2,,  366 

Pyrometer,  491 

Prophylaxis  in  relation  to  crown  and 
bridge-work,  367 

Radiographs,  65,  77,  87,  88,  96,  552,  553, 

555 
Reaming  of  root-canals,  75,  76,  133 
Refining  and  melting  of  gold  scraps,  9 
Reinforcement  of  seamless  gold  crowns, 

205,  206 
Removable  bridge-work,  371 
attachments  for,  372 

comparative  value  of,  408 
comparative    value    of    the    dif- 
ferent forms,  408 
connecting  bars  for  sections  of, 

453>  454,  460 
construction  of,  411 
plate  bridge-work,  441 
saddle  bridge-work,  428 
Removal  of  crowns  and  bridges,  343,  345 

a  post,  343 
Repair  of  crown  and  bridge- work,  337, 
346 
Dr.  Bryant's  method,  338 
counter-sunk  pin-hole  method, 

339 
of  gold  crowns,  346 
Replaceable  porcelain  facings,  299 
Dimlow,  304 
Evslin,  303 
Ideal,  302 
Steele,  301 
Stewart,  303 
Requirements  in  bridgement,  principles 
involved,  274 
crown- work,  no 
inlay- work,  222 
Retaining  inlaj'  abutments,  392 
Richmond  crown,  original  forms  of  as 

introduced,  102 
Roach  attachments,  463 

sectional  impression  trays,  22 
wax  absorber  in  inlay- work,  230 
Root  facers,  120,  122 

canals,  preparation  of,  72 
treatment  and  disinfection,  79,  81 
method  of  filling,  83,  84,  85,  86,  87 
method  of  treatment,  72 


Root  facers,  122 
canal  drier,  80 
caps  cast,  208 
reamers  and  facers,  Ottolingui,  122, 

133 
trimmers,  Evans,  122 
Roots  decayed  apart  at  the  bifurcation, 

249,  539,  553 
intervening  between  abutments,  331 
special   preparation    of    badly    de- 
cayed, 129 
Rouge  paste  for  use  in  filling,  293 

Sanitary  methods  with  cemented  bridge- 
work,  367 
bridge,  325 
porcelain     and    gold    bridge,    326, 

550 
Schweitzer  wax  sprue  former,  51 

exit  vent  in  casting,  51 
Screws  to  support  crowns,  104,  131 
Seamless  gold  caps,  194,  196 
Seamless  gold  crowns,  194 

process  of  adjustment  and  inser- 
tion, 203 
method  of  contouring,  199 
method  of  forming  from  an  im- 
pression,  194,   197,   198 
ready  made,  203,  207 
Seamless  open-faced  crown,  310 
Seamless  root-cap  for  incisors,  194 
Sectional  detachable  bridge- work,  362 
impression  trays,  Roach,  22 
impressions,  21 
Sectional  mold  method  of  making  seam- 
less gold  contour  crowns,  201 
Self -cleansing  spaces  in  bridge-work,  287 
Selection  of  porcelain  teeth,  15 
Sensitive  dentine,  treatment  of,  66 
Shapes  of  necks  of  teeth,  114,  152 
Shaping  teeth  and  roots  for  crowning, 
119 
process  of,  119 
when  badly  decayed,  129 
instruments,    used,    120,    122, 
123 
Shears  for  cutting  metallic  collars,  3,  153 
Shoulders    on    the    anterior    teeth    for 

occlusioUj^  305 
Silicate  cement,  use  of  in  inlay  work, 
266 


INDEX 


567 


Silver  solder,  12 

Slitting  and  contracting  neck  of  a  seam- 
less gold  crown,  199 
Slanting  fractures  of  natural  teeth,  254 
Slots  for  anchorage  bars,  295,  320,  335, 

362,  392,  552 
Solder,  gold,  formulas  for,  9 

excess  of  in  crown,  to  correct,   256 
hard  flowing,   11 
.  platinum,  12 
silver,  12 
Solder  fillings,  11 

fluxed,  method  of  preparing,  1 2 
method  of  using,  12 
vaselined,  12 
Solder  pointer,  39 
Soldering,  33 

block  for,  35 
invertments  for,  Z2>-:  182 
open  flame,   40 

practice  dummies  for  stuc^ents,  40 
union  by  sweating,  41 
with  compound  blow-pipe  flame,  41 
Solid  gold  crowns,  307 

dummies,  306,  437 
tips  for  abraded  anterior  teeth,  232 
Special  preparation   of   badly   decayed 

teeth  or  roots,  129 
Splinting  in  cases  of  pyorrhea,  333 
Split  post  swaging  devise,  Weinstein's, 
378 
burnisher,  378 
Split  bar  bridge  attachment,  402,  425 
Stamping  machine  for  seamless  metallic 

caps,  196 
Staple  crown,  314 
State  Board  bridge,  New  York,  40 
Steele  facing,  301 
Sterilization  of  root-canals,  79-81 
Stewart  facing,  393 
Strengthening  gold  seamless  crowns,  205, 

206 
Structure  of  flame,  36 
Sulfuric  acid,  care  in  the  use  of, 
77,  93 


Sulfuric  acid,  to  open  up  canals,  77 
Swager,  use  of,  31,  32,  150,  164 
Sweating,  to  unite  by,  41 
Syringes,  666,  90 

abscess,  66 

hot  air,  80 

Temporary  crown,  145 

Thickness  of  plates  suitable  in  crown- 
work,  7,  8,  146,  147,  379,  388 

Tin,  alloys  of,  14 

Tips,  gold  for  contouring  natural  crowns 
and  in  cases  of  abrasion,  232, 
234,  5^6 

Trays,  for  in'ay  impression    237,  238 
sectjona',  21,  22 
to  bake  porcelain  on   521 

Trimmers,  root,  3   122 

Tube  and  split  post  anterior  crowns,  387 

Tweezers,  clamps,  3,  152 

Union  of  gold  by  sweating,  41 

Van  Woertz  trays  for  inlay  impressions, 

239 
Veneer  porcelain  facings,  16 
Vulcanite  attachment  for  teeth  to  sad- 
dles, 439 
extension  bridge,  440 

Warping  of  bridge-work  in  soldering,  292 
to  prevent,  292,  295,  296,  325 
Wax  absorber  for  inlay  wax,  230 
cement,   15 
to  cause  to  adhere  to  metal  and 

porcelain,  15 
model  to  cast,   to  prevent   distor- 
tion of,  53 
Wheels,  for  trimming  teeth,  3,  121,  122 
White,  S.  S.,  detached  post  crown,  134 
Wire  for  post  or  pins,  7,  131 

Zinc  oxychloride,  use  of,  84,  88 

oxyphosphate  for  cementation,  139 


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